Cellular and humoral immunity to leukemia cells in BCG-induced growth control of a murine leukemia

The antitumor effects of weekly iv injections of 1.0 mg BCG and/or sc injections of 10(7) irradiated leukemia cells were studied in an isogeneic, transplantable lymphoid leukemia in the C57BL/6 mouse. The injections were started at day 1 after ip inoculation of 10(5) leukemia cells. BCG prolonged the survival time of most animals and cured 22%. BCG plus irradiated cells cured only about 10% of the mice, and irradiated cells alone had no curative effect. Individual tumor-bearing mice in the various experimental groups were examined with respect to ascites tumor cell number; complement-dependent cytotoxic antibodies in sera; direct and antibody-dependent cytotoxicity to tumor cells of lymphoid cells from peritoneal fluid, the spleen, and peripheral lymph nodes; and the cytology of ascites, the spleen, and lymph nodes. Only the antibody-dependent lymphocyte-mediated cytotoxicity (ADLMC) was correlated with the ascites tumor cell number, since the ADLMC was high only in mice with a tumor cell number less than that of the controls. Furthermore, since mice with a low tumor cell number had predominantly only lymphocytes as the nonmalignant cell type in their peritoneal fluid, ADLMC may have had an important role in BCG-induced control of tumor growth.     

Mechanism of action of BCG-tumor cell vaccines in the generation of systemic tumor immunity. II. Influence of the local inflammatory response on immune reactivity

The intradermal injection of a vaccine composed of 10(7) X-irradiated syngeneic hepatocarcinoma line 10 (L10) cells admixed with 10(8) Mycobacterium bovis strain BCG into inbred Sewall Wright strain 2 guinea pigs induces a local inflammatory reaction and effectively immunizes against a contralateral challenge with viable L10 cells. The relationship between the local inflammatory reaction and the generation of tumor immunity was studied. Immunization against L10 was most effective when both L10 cells and BCG were injected into the same site, less effective when they were injected into separate sites with common lymphatic drainage, and not effective when they were injected at totally separate sites. Enzymatic dissociation of dermal vaccination sites revealed that vaccination with BCG and L10 cells combined induced a significantly greater inflammatory response than did vaccination with BCG alone or L10 cells alone; the inflammatory response was also greater than the combination of these individual responses, suggesting that BCG and L10 cells interacted synergistically in the elicitation of an inflammatory response. Sites receiving a combined vaccine of BCG and L10 cells were infiltrated rapidly by inflammatory cells, and surgical excision of these sites as early as 24 hours after vaccine administration did not affect significantly the development of immune responsiveness. However, vaccination sites induced by the injection of BCG and L10 cells at separate but adjacent sites were slowly infiltrated by inflammatory cells, and surgical removal of these sites within 96 hours of vaccination inhibited later immune responsiveness. Quantitative cellular analysis of these inflammatory reactions showed that inflammation was related to tumor-reactive immunity such that the greater the initial inflammatory process, the greater the resistance to tumor challenge.     

Eliciting T cell immunity against poorly immunogenic tumors by immunization with dendritic cell-tumor fusion vaccines

Dendritic cells (DCs) are the most effective APCs and are being studied as natural adjuvants or Ag delivery vehicles to elicit T cell-mediated antitumor immunity. This study examined whether inoculation of DCs fused with poorly immunogenic tumor cells elicited tumor-reactive T cells for adoptive immunotherapy. DCs derived from bone marrow of C57BL/6 (B6) mice were fused with syngeneic B16 melanoma or RMA-S lymphoma cells by polyethylene glycol. The B16/DC and RMA-S/DC fusion hybrids expressed MHC class I, class II Ags, costimulatory molecules, as well as DC-specific and tumor-derived surface markers. The tumor/DC hybrids were capable of processing and presenting tumor-derived Ags, and immunization of B6 mice with irradiated B16/DC or RMA-S/DC vaccine elicited tumor-specific CTL activities. Vaccination of B6 mice with irradiated B16/DC fusion preparations induced partial host protective immunity against B16 tumor challenge. Reduced tumor incidence and prolonged survival time were observed. Adoptive transfer of T cells derived from B16/DC vaccine-primed lymph nodes into B16 tumor-bearing mice greatly reduced the number of established pulmonary metastases with or without in vivo administration of IL-2. Moreover, adoptive transfer of RMA-S/DC vaccine-primed, cultured lymph node T cells eradicated disseminated FBL-3 tumor. The results demonstrate that tumor/DC fusion products are effective cellular vaccines for eliciting T cell-mediated antitumor immunity.     

Regression of Ehrlich ascites carcinoma in BCG-sensitized mice

Intraperitoneal inoculation of CF1 mice with Bacillus Calmette-Guérin (BCG) protected many of them against the ascites form of Ehrlich carcinoma; and, for those that developed cancer, complete regression occurred in up to 50% of the cases at an advanced state of the neoplastic disease. In contrast, when a booster dose of BCG was administered in admixture with tumor cells, the incidence of the tumor was lower and tumor regressions were very rarely observed in mice that developed cancer. Trypan blue, an inhibitor of lysosomal enzymes of macrophages, was found to markedly suppress the natural (innate) antitumor resistance of control mice as well as the acquired resistance and tumor regressions of BCG-sensitized mice. Moreover, a comparison of the cytotoxic activity of the adherent (macrophages) and nonadherent (predominantly lymphocytes) cells isolated from the peritoneal cavity of BCG-sensitized mice, as measured by the inhibition of DNA synthesis, revealed that the effector cells were amongst the macrophages. In contrast, spleen macrophages were devoid of cytotoxicity. The spleen lymphocytes from both BCG-sensitized and control mice possessed about the same significant cytotoxic activity. These results indicate that the activated peritoneal macrophages, induced by a local injection of BCG, could play an important role in the antitumor immunity against Ehrlich carcinoma.     

Bacillus Calmette-Guérin potentiates monocyte responses to lipopolysaccharide-induced tumor necrosis factor and interleukin-1, but not interleukin-6 in bladder cancer patients

During the past decade, particular attention has been focused on treatment of bladder cancer patients with the bacterial agent bacillus Calmette-Guérin (BCG). In these studies, bladder cancer patients were instilled with BCG (75 mg/50 ml) once per week for 6 weeks, 1-2 weeks following trans-urethral resection of the bladder. Cystoscopy was performed after 6 weeks and, unless tumor progression was present, monthly treatments were given for 1 year. Blood was drawn 2 h after the last instillation, and monocytes were isolated (5 x 10(6) cells/ml) and treated, or not, with lipopolysaccharide (LPS) (20 microgram/ml) for tumor necrosis factor alpha (TNF alpha), interleukin-1 alpha (IL-1 alpha) and interleukin-6 (IL-6) release. The levels of monokines were determined by a monokine-specific enzyme-linked immunosorbent assay. Our results clearly show that, after 18 h incubation, macrophages from BCG-treated bladder cancer patients produced from 2.8- to 1.9-fold and from 2.0- to 1.3-fold greater amounts of TNF alpha and IL-1 alpha respectively, compared to macrophages from healthy controls, 5-fold higher than bladder cancer patients not treated with BCG. IL-6 was not affected. In another set of experiments macrophages (5 x 10(6) cells/ml) from healthy subjects were pretreated, or not, with BCG (100 micrograms/ml) overnight and treated, or not, with LPS 20 microgram/ml alone and in combination with interleukin-1 receptor antagonist (IL-1ra) 250 ng/ml. Macrophages treated with BCG had a strong stimulatory effect on IL-1 alpha release (9.45 ng/ml) while LPS was less effective (3.59 ng/ml). The combination of BCG plus LPS produced an additive effect on IL-1 alpha release (13.71 ng/ml) compared to the effect of the compound alone. The addition of IL-1ra (250 ng/ml) to BCG was not effective, while when IL-1ra was added to BCG plus LPS only a partial inhibition of IL-1 alpha release was found (9.83 ng/ml), compared to BCG plus LPS without IL-1ra (13.71 ng/ml). These effects seem to be related to the inhibition of IL-1 alpha stimulated with LPS, but not BCG. The priming effect of BCG exerted on LPS-stimulated monocyte production of TNF alpha and IL-1 alpha from bladder cancer patients led us to study the possible modulation of fibrinogen and C-reactive protein in the serum of BCG-treated cancer patients. The plasma levels of fibrinogen and C-reactive protein were higher (approximately twice) in BCG-treated patients compared to values obtained in untreated patients or healthy controls. We conclude that the beneficial immunotherapeutic effects of BCG in bladder cancer patients are related to its capacity to prime macrophages to enhance the release of TNF alpha and IL-1 alpha, but not IL-6 in response to physiological secondary stimuli, or through the direct stimulation of BCG on IL-1 alpha or TNF alpha, which are directly involved in the killing of cancer cells.(ABSTRACT TRUNCATED AT 400 WORDS)     

Ganciclovir chemoablation of herpes thymidine kinase suicide gene-modified tumors produces tumor necrosis and induces systemic immune responses

The goal of this work was to identify potential host immune responses to thymidine kinase (TK) suicide gene-modified tumors undergoing chemoablation induced by the prodrug ganciclovir (GCV). The aims were to measure the efficacy and specificity of immunity induced against unmodified tumor, to identify qualitative or quantitative changes in the host response to TK+ tumors undergoing chemoablation that may contribute to the induction of antitumor immunity, and to compare critically the induction of immunity by chemoablation of TK-modified tumors with that of other methods of immunization in this tumor model and in response to other well-defined model antigens. Animals treated with TK+ tumors and GCV developed specific resistance to rechallenge with unmodified tumor. GCV induced significant tumor necrosis, which was associated with a pronounced host cell infiltrate composed of polymorphonuclear cells, both CD4+ and CD8+ T lymphocytes, and increased intratumoral IL-12. Cyclophosphamide-treated mice exhibited no such host response despite the induction of tumor necrosis. CTL responses to defined antigens in TK+ cells were greater in animals treated with prodrug than were those in animals not treated with prodrug but harboring live TK+ cells. Similar degrees of immunity were produced by immunization with irradiated cells.     

PSA for outcome prediction and posttreatment evaluation following radiation for prostate cancer: do we know how to use it?

The specific aim of this study was to examine the prophylactic as well as the therapeutic efficacies of irradiated mouse CT26 colon cancer cells, infected with recombinant adenoviruses harboring cDNAs specific for granulocyte macrophage-colony-stimulating factor (GM-CSF), interferon (IFN-gamma) and monocyte chemotactic protein1 (MCP-1). Results showed that tumor cells secrete the respective cytokines for several days after infection and subsequent irradiation. Vaccination with irradiated GM-CSF-secreting CT26 cells protected 90% of syngeneic mice challenged with live parental cells. On the other hand, vaccination with irradiated IFNgamma or MCP-1-secreting CT26 cells totally failed to protect mice from tumor development after challenge with parental cells. None of the tumor-free mice initially vaccinated with irradiated GM-CSF-producing CT26 cells developed tumor upon repeated challenge with parental cells during the entire observation period. The establishment of specific and long-lasting antitumor immunity following vaccination with GM-CSF-producing tumor cells requires the simultaneous presence of GM-CSF and tumor antigen at the vaccine site. Depletion of CD8+ cells, but not CD4+ cells, blocked the vaccine efficacy of GM-CSF-producing tumor cells. Subcutaneous injection of irradiated GM-CSF-producing CT26 cells also effectively prevented the growth of a small load of parental tumor that was implanted 3 days earlier or the development of metastatic foci in the lung from intravenously injected parental cells either 7 days before or 3 days after vaccination. Our data thus show that, in these experimental tumor models, subcutaneous injection of irradiated tumor cells adenovirally, transduced with the GM-CSF gene leads not only to prevention of growth of subsequently implanted tumor but also to elimination of pre-existing and metastatic tumors.     

The Friedreich's ataxia mutation confers cellular sensitivity to oxidant stress which is rescued by chelators of iron and calcium and inhibitors of apoptosis

Interleukin 12 (IL-12) exhibits anti-tumor activity in a variety of laboratory models. Although IL-12 itself activates strong anti-tumor activity, the combination of vaccine therapy with IL-2-transduced tumor cells and systemic rIL-12 has been shown to cure tumor-bearing mice more effectively than either rIL-12 or IL-2-transduced tumor vaccines alone. In the present study, regression of brain tumors established in naive mice was obtained by combined administration of an intratumoral injection of a single dose of IL-2-producing glioma cells (SR/IL-2 cells) and recombinant IL-12. Intraperitoneal rIL-12 administration substantially delayed the growth of s.c. inoculated gliomas, but not of gliomas located in the brain. Although vaccination with SR/IL-2 cells alone was not effective against s.c. inoculated gliomas, the combination therapy of vaccination with irradiated SR/IL-2 cells and systemic rIL-12 was more effective than rIL-12 alone. In our brain-tumor model, intratumoral administration of irradiated SR/IL-2 cells and of rIL-12 remarkably prolonged survival as compared with untreated mice. Efficacy was reduced when studies were performed in mice depleted of CD8+ cells or NK cells. Mice cured of their intracerebral tumors by combined administration of SR/IL-2 cells and rIL-12 demonstrated protective immunity upon rechallenge. In summary, the therapeutic potential for control of tumor growth by intratumoral administration of IL-2-producing glioma cells and rIL-12 may be useful in the development of treatment for patients with glioma.     

Effect of dose, schedule, and route of administration on the in vivo toxicity and antitumor activity of two activated sulfhydryl derivatives of cyclophosphamide

Two cyclophosphamide (CP) derivatives, 4-S-(hexane-6-ol)-sulfidocyclophosphamide (C-1) and 4-S-(propionic acid)-sulfidocyclophosphamide (C-2), that hydrolyze spontaneously under physiological conditions to 4-hydroxycyclophosphamide, are compared to CP for antitumor activity in male C57BL/6 x DBA/2 F1 mice with ascites L1210 leukemia or solid Lewis lung carcinoma. When C-1 or C-2 is administered i.p. as a single injection at 10% lethal dose (approximately LD10) to mice bearing L1210 (1 x 10(5) cells i.p.), early treatment produces a 5- to 6-log tumor cell kill and results in substantial numbers of long-term survivors (greater than or equal to 30 days). Such antitumor activity is comparable to that of CP treatment. However, i.p. administration of either sulfido derivative produces liver atrophy and fibrosis of hepatic capsular structures. Hepatotoxicity is eliminated if single-dose C-2 (less than or equal to LD10) is administered i.v.; however, when administered by this route, C-2 results in only a 1-log cell kill of i.v. implanted leukemic cells as compared to the 4-log tumor cell kill obtained with CP given i.v. In addition to hepatotoxicity, C-2 causes an acute and dose-limiting toxicity in mice, manifested by severe muscular spasms and cessation of breathing. In the treatment of advanced L1210, C-2 shows no therapeutic advantage over CP. When mice bearing s.c. Lewis lung carcinoma receive early i.p. treatment with CP, C-1, or C-2, each drug results in long-term tumor-free survivors. However, CP (< LD10) consistently cures all mice, whereas C-1 or C-2 (approximately LD10) produces only 10 to 30% tumor-free survivors. These data suggest that, in the L1210 and Lewis lung tumor systems studied, the two activated CP derivatives offer no therapeutic advantage over CP. In addition, two forms of toxicity occur with these derivatives that do not occur with CP.     

Activation of CD8 T cells with specificity for mycobacterial heat shock protein 60 in Mycobacterium bovis bacillus Calmette-Guérin-vaccinated mice

Heat shock protein 60 (hsp60)-specific CD8 T cells lysed Mycobacterium bovis BCG-infected macrophages in vitro and adoptively transferred protection against mycobacterial infection. Moreover, CD8 T cells with this hsp60 specificity were activated in vivo by BCG vaccination. Our studies suggest there is participation of hsp60-specific CD8 T cells in BCG-induced immunity.     

Sustained cytokine delivery for anticancer vaccination: liposomes as alternative for gene-transfected tumor cells

Vaccination with tumor cells genetically engineered to produce interleukin (IL)-2 is an attractive strategy to enhance antitumor immune responses. The improved antitumor immunity upon vaccination with IL-2 gene-modified tumor cells may be due to the prolonged presence of the cytokine at the vaccination site. Because liposomes have been used for sustained delivery of a variety of agents, we compared the protective effect of vaccines consisting of IL-2 gene-modified B16 melanoma cells to that of vaccines composed of IL-2 liposomes and irradiated melanoma cells. The results indicate that both approaches equally protect against a lethal challenge with B16 melanoma cells. More than 20% of the protected animals developed vitiligo at the vaccination and/or tumor challenge site.     

Cellular requirements for tumor-specific immunity elicited by heat shock proteins: tumor rejection antigen gp96 primes CD8+ T cells in vivo

Purified preparations of 96-kDa heat shock proteins (gp96) have been previously shown to elicit tumor-specific immunity to the tumor from which gp96 is obtained but not to antigenically distinct chemically induced tumors. The cellular requirements of gp96-elicited immunity have been examined. It is observed that depletion of CD8+, but not CD4+, T cells in the priming phase abrogates the immunity elicited by gp96. The CD8+ T cells elicited by immunization with gp96 are active at least up to 5 weeks after immunization. Depletion of macrophages by treatment of mice with carrageenan during the priming phase also results in loss of gp96-elicited immunity. In the effector phase, all three compartments, CD4+ and CD8+ T cells and macrophages, are required. Immunity elicited by whole irradiated tumor cells shows a different profile of cellular requirements. In contrast to immunization with gp96, depletion of CD4+, but not CD8+, T cells during priming with whole tumor cells abrogates tumor immunity. Further, ablation of macrophage function during priming or effector phases has no effect on tumor immunity elicited by whole cells. Our results suggest the existence of a macrophage-dependent and a macrophage-independent pathway of tumor immunity. Our observations also show that in spite of exogenous administration, vaccination with gp96 preparations elicits a CD8+ T-cell response in vivo, and it is therefore a useful method of vaccination against cancer and infectious diseases.     

Immunotherapy in the management of myelogenous leukemia

Now that it has been clearly established that tumor-associated antigens exist in acute leukemia in man, as in animals, the possibility of stimulating the patient's immune system to react against them arises. In animal experiments the most effective method of influencing the progress of leukemia after the implantation of living malignant cells has been a combination of nonspecific stimulation of the reticuloendothelial system, with agents such as BCG or Corynebacterium parvum, either with chemotherapy or with specific immunization with irradiated leukemic cells. However, such treatment is only effective if the number of living malignant cells is small as it takes a powerful immune response to overcome even a small number of malignant cells. It is for these reasons that most of the studies in man have been on patients with acute leukemia in remission. Mathé, in 1969, produced evidence that BCG and irradiated allogenic leukemia cells could lengthen the duration of remission in ALL in children. However, later results of intensive combination chemotherapy, together with prophylactic treatment of the central nervous system by Pinkel and his colleagues, were so encouraging that immunotherapy is not felt to be needed and therefore is not being extensively used in this form of leukemia at the moment. The situation in AML, particularly in adults, is completely different. The maintenance of remission with chemotherapy in this type of leukemia is difficult and relapses occur quite rapidly. Various centers have now shown that both remission lengths and overall survival are significantly prolonged by using BCG with or without irradiated allogenic leukemia cells.     

Absolute or relative measurement of carbohydrate-deficient transferrin in serum? Experiences with three immunological assays

The mechanism of anti-tumour activity by BCG is not known clearly. However, many studies suggest that immunological response is related to effectiveness of intravesical instillation of BCG in the therapy for superficial bladder carcinoma. Peripheral blood mononuclear cells (PBMC), urine and serum were obtained from patients with superficial carcinoma at various times during the course of BCG instillation. Urine of patients showed increased levels of IL-1beta, IL-2, IL-6, tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma) and macrophage colony-stimulating factor (M-CSF) after BCG instillation. Levels of IL-2 and IFN-gamma in the serum also increased after BCG instillation, but IL-1beta, IL-6, TNF-alpha and M-CSF were not detectable. Maximal levels of IL-2 and IFN-gamma in the urine or serum were shown after the fourth instillation. BCG-induced killer cell activity in PBMC increased significantly after the third BCG instillation. These results suggest that BCG instillation involved not only local immunological efforts but also systemic immune responses. Tumour-free patients produced higher BCG-induced killer cell activity than tumour recurrence patients. BCG-induced killer cell activity may be useful for monitoring the effectiveness of intravesical BCG instillation.     

The central role of CD4(+) T cells in the antitumor immune response

The induction of optimal systemic antitumor immunity involves the priming of both CD4(+) and CD8(+) T cells specific for tumor-associated antigens. The role of CD4(+) T helper cells (Th) in this response has been largely attributed to providing regulatory signals required for the priming of major histocompatibility complex class I restricted CD8(+) cytolytic T lymphocytes, which are thought to serve as the dominant effector cell mediating tumor killing. However, analysis of the effector phase of tumor rejection induced by vaccination with irradiated tumor cells transduced to secrete granulocyte/macrophage colony-stimulating factor indicates a far broader role for CD4(+) T cells in orchestrating the host response to tumor. This form of immunization leads to the simultaneous induction of Th1 and Th2 responses, both of which are required for maximal systemic antitumor immunity. Cytokines produced by these CD4(+) T cells activate eosinophils as well as macrophages that produce both superoxide and nitric oxide. Both of these cell types then collaborate within the site of tumor challenge to cause its destruction.     

Cryopreservation of rat and mouse hepatocytes. II. Assessment of metabolic capacity using testosterone metabolism

Cryopreservation of hepatocytes is widely used, but to validate the use of cryopreserved (CP) hepatocytes in metabolic studies, CP cells must compare favorably with fresh cell activities. We have assessed the metabolic capacity of fresh and CP rat and mouse hepatocytes in primary culture. Total cytochrome P450 (P450) contents and metabolism of testosterone were measured up to 72 hr in culture. At 0 hr, total P approximately 450 in CP rat hepatocytes was 102.5 +/- 32.8 pmol/10(6) cells, compared with fresh rat hepatocytes that had 148.2 +/- 75.7 pmol/10(6) cells. The P450 contents of mouse hepatocytes were also unaltered by cryopreservation (176.7 +/- 56.0 pmol/ 10(6) fresh cells; 196.4 +/- 59.9 pmol/10(6) CP cells). There were no significant differences in the total P450 contents of fresh and CP rat and mouse cell cultures with time over 72 hr in culture. The overall metabolism of testosterone was lower in CP suspensions than in freshly isolated hepatocytes. When CP hepatocyte suspensions were permeabilized (with digitonin) and incubated with NADPH and ATP, testosterone metabolism was significantly increased. Testosterone hydroxylase activities (16 alpha-, 6 beta-, 2 alpha-, and 7 alpha-hydroxylase) were equivalent in fresh and CP rat hepatocytes over 72 hr in culture. There was a marked and sustained loss of 6 beta-hydroxylase activity in CP mouse hepatocyte cultures, compared with fresh hepatocytes throughout 72 hr in culture (436.9 +/- 118.0 pmol/min/10(6) cells and 37.3 +/- 41.0 pmol/min/10(6) cells at 72 hr in fresh and CP mouse hepatocytes, respectively). The total metabolism of testosterone was, however, unaffected because 16 alpha-hydroxylase activity increased in CP mouse hepatocytes (475.4 +/- 80.8 pmol/min/10(6) CP cells, compared with 148.7 +/- 39.4 pmol/min/10(6) fresh cells).     

Phacoanaphylactic endophthalmitis: echographic diagnosis of phacoanaphylactic endophthalmitis

Immunization of CC57Br mice with irradiated Krebs-2 carcinoma cells renders no influence on the rate of ascites aggravation in subsequent transplantation of the tumor but increases considerably life-terms of tumor-bearing animals. Immunization with tumor cells in combination with not high doses of BCG results in a reverse development of ascites in some mice and a complete disappearance of tumor in them. With increased dosage of the vaccine the number of animals with ascites regression is increased, but their life-terms are reduced due to reactivation of the tumor process and, presumably, to the development of autoimmune lesions.     

Influence of mouse strain and vaccine viability on T-cell responses induced by Mycobacterium bovis bacillus Calmette-Guérin

C57BL/6 and BALB/c mice were vaccinated with either live or heat-killed Mycobacterium bovis bacillus Calmette-Guérin (BCG) organisms, and splenic T cells were used to screen the stimulatory potential of fractionated somatic and secreted mycobacterial proteins by production of gamma interferon (IFN-gamma). Maximum responses were obtained with fractionated secreted proteins of Mycobacterium tuberculosis. There was no single dominant antigen, but five regions of mycobacterial proteins induced high concentrations of IFN-gamma. However, only two of the five regions stimulated T cells from both mouse strains: two were exclusively recognized by T cells from BALB/c mice, and one was exclusively recognized by T cells from C57BL/6 mice. T cells from mice vaccinated with heat-killed M. bovis BCG organisms failed to respond to fractionated secreted proteins but recognized several somatic antigen fractions. As late as 1 year after primary vaccination, memory T cells responded to similar protein regions, and IFN-gamma production was intensified by secondary infection. Our data confirm a central role for secreted proteins in immunity to mycobacteria. Moreover, we demonstrate that a major set of mycobacterium-reactive T cells is stimulated only by vaccination with live but not with heat-killed M. bovis BCG organisms. Because a major impact of genetic host factors on antigen recognition was observed, we favor the use of live carrier organisms which secrete mycobacterial proteins over subunit vaccines as an improved antituberculosis vaccine.     

Using the outcome-based quality improvement model and OASIS to improve HMO patients'' outcomes. Outcome Assessment and Information Set

In Japan, BCG vaccination, which covers more than 90% of infants, has been given according to the national immunization policy. Moreover, first-grade children in elementary school are screened with tuberculin skin test, and those who show negative reaction in the Japanese standard, i.e. size of erythema less than 10 mm, are re-vaccinated with BCG according to the Tuberculosis Prevention Law. However, since the incidence of tuberculosis among children below age 14 is as low as 1.5/100,000 in Japan, it is time to reconsider the BCG vaccination policy. As the first step to assess the efficiency of the present program, we observed the occurrence of Koch's phenomenon after BCG vaccination in elementary school children in Chiba City in 1995 and 1996, and we introduced the two-step tuberculin test to elementary school children in 1997. Among 180 BCG vaccinated children in 1995 and 1996, 168 (93.3%) had been vaccinated by 4-year of age. We could follow local reaction of BCG re-vaccination and observed Koch's phenomenon in 117 (69.6%, 95% C.I. of 62.7-76.6%). Among 92 tuberculin negative children in 1997, 85 (92.4%) had been vaccinated by 4-year of age. In the two-step tuberculin test program of 85 initial negative-reactors, 63 (74.1%, 95% C.I. of 64.8-83.4%) turned to positive by the second test. Those results suggest that more than 69% of tuberculin-negative school children who were vaccinated previously maintained immunity with BCG. Our studies raised a problem of the current BCG re-vaccination policy that depends on the result of tuberculin test. Due to the discrepancy between tuberculin allergy and immunity in tuberculosis, many school children may be given BCG vaccination unnecessarily. Taking into consideration the incidence of tuberculosis in children, discontinuation of BCG re-vaccination policy at elementary school entrance should be considered.     

Cytotoxicity and tolerance to DNA adducts of alicyclic mixed amine platinum(II) homologs in tumor models sensitive and resistant to cisplatin or tetraplatin

Structure-cytotoxicity relationships for six alicyclic cis-(NH3)(R-NH2)Cl2Pt(II) complexes, where R=C3H5, C4H7, C5H9, C6H11, C7H13 and C8H15 (complexes abbreviated C3, C4, C5, C6, C7 and C8, respectively), were evaluated against four sensitive (L1210/0, A2780, FSaIIC and Colon 26), two cisplatin-resistant (L1210/DDP and 2780CP) and two tetraplatin-resistant (L1210/DACH and 2780TP) murine and human tumor cell lines. The studies demonstrated that in general the structure of C6 was optimal within the homologous series for cytotoxic potency against these tumor models. Biochemical pharmacologic studies indicated that the greater sensitivity of cells to C6 could be correlated with their low tolerance to DNA damage induced by this homolog. These results provide evidence for the alicyclic ring size as a structural determinant of DNA damage tolerance and anti-tumor activity in sensitive and resistant tumor cells.