A longitudinal study of immunologic reactivity in leprosy patients treated with immunotherapy

More than 150 leprosy patients treated with multidrug therapy (MDT) plus immunotherapy (IMT) with a mixture of heat-killed Mycobacterium leprae plus live BCG were studied in relation to humoral and cell-mediated immune responses. Many previously had received prolonged sulfone monotherapy. Patients received 2 to 10 doses of IMT in a period of 1 to 3 years, depending upon their clinical form of leprosy. The patients were followed up for 5 to 10 years with repeated determinations of antibody levels to phenolic glycolipid-I; lymphoproliferative (LTT) responses to soluble extract of M. leprae, to whole bacilli and to BCG, skin-test responses and bacterial indexes (BIs). After MDT plus IMT there was a statistically significant decrease of antibody levels in the multibacillary (MB) group. The BI decreased proportionally to the ELISA results. LTT increased to M. leprae antigens, especially to soluble extract, in a high percentage of these patients (34% of LL patients positive). Lepromin positivity in MB patients increased from 5% initially positive to 75% at the cut-off during this follow up. These results show substantial early and persistent cell-mediated reactivity to M. leprae in many MB patients treated with MDT-IMT, confirming and expanding previously published data.     

Characterization of phenolic glycolipid-I (PGL-I) like antigen in renal cell carcinoma

BACKGROUND: We investigated whether phenolic glycolipid-I (PGL-I) produced by Mycobacterium leprae (M. leprae), can be used as a marker of renal tumors. METHODS: Using a preparted anti-PGL-I monoclonal antibody (SF-I), anti-PGL-I group antibodies and PGL-I group antigens were detected and PGL-I immunohistologic staining were performed. RESULTS: The titer of anti-PGL-I antibody in patients with renal cell carcinoma was 0.283 +/- 0.103, showing a trend of rising titer of anti-PGL-I group antibody with higher cytologic atypia. When compared by the extent of tumor infiltration, a high antibody titer was observed in stage 4 infiltration group. Regarding the PGL-I group antigen that was detected using SF-1 in the urine of patients with renal cell carcinoma, no relationships between the positive rte of the antigens with common antigenicity to PGL-I and the grade of carcinoma were observed. However, in terms of the extent of tumor infiltration, a trend that the positive rate for PGL-I group antigen increased with the progression of cancer stage was seen. The Western blot assay of the urine of patients with renal cell carcinoma following electrophoresis revealed a change around 40 KD. The immunohistologic stains with SF-1 disclosed a predominance in the proximal kidney tubule. CONCLUSION: Using PGL-I group antigen and PGL-I group antibody as markers of renal cell carcinoma, a rapid and precise measurement may be provided.     

Delayed-type hypersensitivity to Mycobacterium leprae soluble antigens as a test for infection with the leprosy bacillus

BACKGROUND: Mycobacterium leprae (M. leprae) soluble antigen (MLSA) reagents have been developed with the aim of finding a reagent, comparable to tuberculin, which could identify individuals infected with the leprosy bacillus. They have yet to be evaluated fully in human populations. METHODS: More than 15000 individuals living in a leprosy endemic area of northern Malawi were skin tested with one of five batches of MLSA prepared using two different protocols. The main difference in preparation was the introduction of a high G centrifugation step in the preparation of the last three ('second-generation') batches. RESULTS: The prevalence of skin-test positivity (delayed-type hypersensitivity (DTH)) and association with the presence of a BCG scar were greater for first (batches A6, A22) than second (batches AB53, CD5, CD19) generation reagents. The association of positivity with M. leprae infection was investigated by comparing results among known (household) contacts of leprosy cases, and among newly diagnosed leprosy patients with those in the general population. While positivity to 'first-generation' antigens appeared to be associated with M. leprae infection, positivity to later antigens was unrelated either to exposure to leprosy cases or presence of leprosy disease. There were geographical differences in the prevalence of DTH to the various batches, probably reflecting exposure to various mycobacteria in the environment. CONCLUSIONS: Our results suggest that the 'second-generation' batches have lost antigens that can detect M. leprae infections, but that they retain one or more antigens which are shared between M. leprae and environmental mycobacteria. Natural exposure to these both sensitizes individuals and provides natural protection against M. leprae infection or disease. Identification of antigens present in these groups of skin test reagents may assist in production of improved skin test reagents.     

A GAUSS program for computing the Foulkes-Davis tracking index for polynomial growth curves

Sixty-five patients initially seropositive for IgM anti-phenolic glycolipid-I (PGL-I) antibodies were tested for antibody levels to PGL-I, lipoarabinomannan (LAM), and the 35-kDa protein of Mycobacterium leprae at regular intervals for up to 30 months following the commencement of multidrug therapy (MDT). There was a steady decline in IgM anti-PGL-I and anti-35-kDa antibody levels to a mean of 17% and 14%, respectively, of the starting level at 24 months. The development of type 1 and type 2 reactions or the presence of drug-resistant organisms in a small number of patients had no significant influence on the changes in antibody level. The rate of decline was similar in different disease categories, but a higher proportion of lepromatous patients remained seropositive at the end of 2 years of treatment than borderline tuberculoid patients. By contrast, the mean IgG anti-LAM antibody levels remained stable or increased. Again the occurrence of type 1 or type 2 reactions had no significant effect on antibody level over 2 years. Falls in the IgM anti-PGL-I antibody levels mirrored the falls in the bacterial index in individual patients and provide an additional parameter for monitoring the response to chemotherapy.     

Gas embolism in obstetrics and gynecology. A review

Recent data suggest that the clinical course of reactional states in leprosy is closely related to the cytokine profile released locally or systemically by the patients. In the present study, patients with erythema nodosum leprosum (ENL) were grouped according to the intensity of their clinical symptoms. Clinical and immunological aspects of ENL and the impact of these parameters on bacterial load were assessed in conjunction with patients' in vitro immune response to mycobacterial antigens. In 10 out of the 17 patients tested, BI (bacterial index) was reduced by at least 1 log from leprosy diagnosis to the onset of their first reactional episode (ENL), as compared to an expected 0.3 log reduction in the unreactional group for the same MDT (multidrug therapy) period. However, no difference in the rate of BI reduction was noted at the end of MDT among ENL and unreactional lepromatous patients. Accordingly, although TNF-alpha (tumor necrosis factor) levels were enhanced in the sera of 70.6% of the ENL patients tested, no relationship was noted between circulating TNF-alpha levels and the decrease in BI detected at the onset of the reactional episode. Evaluation of bacterial viability of M. leprae isolated from the reactional lesions showed no growth in the mouse footpads. Only 20% of the patients demonstrated specific immune response to M. leprae during ENL. Moreover, high levels of soluble IL-2R (interleukin-2 receptor) were present in 78% of the patients. Circulating anti-neural (anti-ceramide and anti-galactocerebroside antibodies) and anti-mycobacterial antibodies were detected in ENL patients' sera as well, which were not related to the clinical course of disease. Our data suggest that bacterial killing is enhanced during reactions. Emergence of specific immune response to M. leprae and the effective role of TNF-alpha in mediating fragmentation of bacteria still need to be clarified.     

Abnormal prostate development in C3(1)-bcl-2 transgenic mice

Two bacillus Calmette-Guérin (BCG)-susceptible mouse strains, BALB/c and C57BL/6, were infected intravenously with Mycobacterium intracellulare, M. avium or M. scrofulaceum and monitored during 3 months for mycobacterial replication and antibody and Th1-type cytokine production in response to cytoplasmic and secreted antigens from M. bovis BCG. Whereas initial colony-forming unit (CFU) counts of M. intracellulare and M. avium were higher in lungs than in spleen, the opposite was observed for M. scrofulaceum. Mycobacterium intracellulare was the most virulent species and its replication could not be controlled in either mouse strain. It also induced the strongest antibody response. Mycobacterium avium was eliminated in both mouse strains and M. scrofulaceum finally was eliminated in C57BL/6 but multiplied in spleen from BALB/c mice. Significant sustained interleukin-2 and interferon-gamma production towards BCG antigens was only found in M. scrofulaceum infection. As in BCG-vaccination, M. scrofulaceum-infected C57BL/6 mice demonstrated a higher response towards whole BCG culture filtrate, BCG extract and purified antigen 85 complex (Ag85) from BCG than did BALB/c mice. The data suggest that the presence of M. scrofulaceum in the environment may possibly interfere in genetically predisposed subjects with BCG vaccine and its protective efficacy against M. tuberculosis.     

Superficial bladder tumors and increased reactivity against mycobacterial antigens before bacillus Calmette-Guerin therapy

PURPOSE: The precise mechanism of action of bacillus Calmette-Guerin (BCG) in bladder cancer treatment remains poorly understood. Whether bladder tumor cells are destroyed by nonspecific mechanisms or targeted by specifically activated lymphocytes recognizing cognate antigens is unclear. To investigate a possible cross-reactivity between BCG and bladder cell tumors, we tested before BCG treatment the lymphoproliferation of peripheral blood lymphocytes against several mycobacterial antigens, including the secreted fibronectin binding antigen 85 complex from BCG (AG 85) in patients with superficial bladder tumors compared to control matched patients. MATERIALS AND METHODS: Using a whole blood assay, T cell response against purified protein derivative, BCG extract, whole BCG, purified AG 85, and the nonspecific mitogens pokeweed and phytohemagglutinin was investigated in 79 patients with superficial bladder tumors before BCG and in 39 control subjects without malignancy matched for age and sex. Neither group had a history of tuberculosis. Lymphoproliferation was measured with a tritiated thymidine uptake assay on day 7 of culture. RESULTS: Of the 79 patients with superficial transitional cell carcinoma, a significant lymphoproliferative response before BCG against PPD, BCG extract, whole BCG and AG 85 was observed in 65 (82.2%), 67 (84.81%), 30 (37.97%) and 49 (62.02%) patients, respectively. Of the 39 controls only 26 (64.1%), 23 (58.9%), 3 (7.7%) and 3 (7.7%) patients, respectively, had a significant lymphoproliferation against PPD, BCG extract, BCG and AG 85 (p >0.05, p = 0.004, p = 0.00001 and p = 0.00001, respectively). In terms of lymphoproliferative levels, patients with superficial transitional cell carcinoma also showed a significantly higher response against PPD (p = 0.000012), BCG extract (p = 0.000001), AG 85 (p = 0.000001), whole BCG (p = 0.00001) and pokeweed (p = 0.01) than controls but not against phytohemagglutinin. CONCLUSIONS: Patients with superficial transitional cell carcinoma demonstrate an increased lymphoproliferation against mycobacterial antigens before BCG compared to control subjects. Although a nonspecific activation of the immune system cannot be excluded at this stage, our data may suggest the possible existence of bladder cancer antigens cross-reactive with mycobacterial antigens responsible for boosting precursor cells witnessing previous contacts with mycobacteria. The implication of these findings in the antitumoral mechanism of action of BCG are under investigation.     

Inhibition of pulmonary granuloma formation in mice by treatment with Mycobacterial protoplasm and immuno-suppressants and its relation to protection against aerosol infection with virulent Mycobacterium tuberculosis

Because the pulmonary granuloma formation by mycobacterial cell walls (CW) is likely mediated by cellular immunity, the effect of specific antigens and various immunosuppressants on pulmonary granuloma formation and protection against virulent m. tuberculosis, strain H37Rv was investigated in mice immunized with oil-treated CW from BCG or M. Tuberculosis, strain Aoyama B. Results of desensitization experiments with specific antigens showed that multiple intravenous injections of BCG protoplasm inhibited the footpad delayed hypersensitivity, macrophage migration inhibitory activity of lung cells and pulmonary granuloma formation as well as the enhancement of resistance against aerosol challenge with M, tuberculosis, strain H37Rv. However, treatment with nonspecific immunosuppressants like con A, silica or carrageenan induced only abrogation of footpad delayed hypersensitivity but not prevention of pulmonary granuloma formation or resistance against aerosol challenge. These results suggest a close relationship between pulmonary granuloma formation and protection against H37Rv in mice immunized with oil-treated mycobacterial CW.     

Pefloxacin in leprosy

Fluoroquinolones, a new class of compounds characterised by broad antimicrobial spectrum including mycobacteria together with limited toxicity, have recently been introduced in the chemotherapy of various human infectious diseases. Pefloxacin, one of the members of this class, was recently demonstrated to be bactericidal against M.leprae in the mouse foot-pad model and clinically beneficial in lepromatous leprosy patients. Clinical response to standard MDT with added pefloxacin in ten previously untreated (both PB and MB) was compared with that in ten similar patients on MDT alone in the present trial. The results of chemotherapy were quantified by a method of clinical scoring. This pilot study showed that addition of pefloxacin led to significant and rapid clinical improvement. There were no side effects attributable to pefloxacin.     

Homologs of Mycobacterium leprae 18-kilodalton and Mycobacterium tuberculosis 19-kilodalton antigens in other mycobacteria

Most of the antigens of Mycobacterium leprae and M. tuberculosis that have been identified are members of stress protein families, which are highly conserved throughout many diverse species. Of the M. leprae and M. tuberculosis antigens identified by monoclonal antibodies, all except the 18-kDa M. leprae antigen and the 19-kDa M. tuberculosis antigen are strongly cross-reaction between these two species and are coded within very similar genes. Studies of T cell reactivity against mycobacterial antigens have indicated that M. tuberculosis bears epitopes that are cross-reactive with the M. leprae 18-kDa antigen, but attempts to identify an 18-kDa antigen-like protein or protein coding sequence in M. tuberculosis have been unsuccessful. We have used a combination of low-stringency DNA hybridization and polymerase chain reaction techniques to identify, isolate, and sequence genes from M. avium and M. intracellulare that are very similar to the 18-kDa antigen gene of M. leprae and others that are homologs of the 19-kDa antigen gene of M. tuberculosis. Unlike M. leprae, which contains a single 18-kDa antigen gene, M. avium and M. intracellulare each have two 18-kDa antigen coding sequences. Although the M. leprae, M. avium, and M. intracellulare 18-kDa antigen genes are all very similar to one another, as are the M. tuberculosis, M. avium, and M. intracellulare 19-kDa antigen genes, we have been unable to detect any 18-kDa antigen-like coding sequences in DNA from M. tuberculosis.     

Leprous neuropathies

Once a terrifying disease, leprosy today has a very hopeful prognosis, provided that it is diagnosed early and treated with modern multidrug chemotherapy, any immunological reactions being recognized quickly and controlled well to prevent (further) peripheral nerve damage after commencing treatment. The diagnosis should be considered in all patients who present with peripheral neuropathy and/or anaesthetic skin lesions who come from or have lived in the tropics and subtropics. Although M. leprae cannot yet be grown in vitro, it is readily grown in experimental animals. A complete gene library has been developed, much of the genome mapped and a number species-specific and common mycobacterial antigens identified. The intricacies of the host-parasite relationship, especially of cell-mediated immunity, and of the important immunological reactions of ENL and reversal reaction have been widely investigated. Modern MDT has caused a dramatic fall in prevalence, although the world annual case detection rate remains at around 600,000 new patients, many being at an early stage of the disease. WHO has launched a campaign to eliminate leprosy as a significant public health risk by the 2000 (with a prevalence of less than 1:10 000 population), which may well be achieved in some endemic countries. Leprosy will, however, remain an important cause of peripheral neuropathy for at least several more decades.     

Molecular and immunological analyses of the Mycobacterium avium homolog of the immunodominant Mycobacterium leprae 35-kilodalton protein

The analysis of host immunity to mycobacteria and the development of discriminatory diagnostic reagents relies on the characterization of conserved and species-specific mycobacterial antigens. In this report, we have characterized the Mycobacterium avium homolog of the highly immunogenic M. leprae 35-kDa protein. The genes encoding these two proteins were well conserved, having 82% DNA identity and 90% identity at the amino acid level. Moreover both proteins, purified from the fast-growing host M. smegmatis, formed multimeric complexes of around 1000 kDa in size and were antigenically related as assessed through their recognition by antibodies and T cells from M. leprae-infected individuals. The 35-kDa protein exhibited significant sequence identity with proteins from Streptomyces griseus and the cyanobacterium Synechoccocus sp. strain PCC 7942 that are up-regulated under conditions of nutrient deprivation. The 67% amino acid identity between the M. avium 35-kDa protein and SrpI of Synechoccocus was spread across the sequences of both proteins, while the homologous regions of the 35-kDa protein and the P3 sporulation protein of S. griseus were interrupted in the P3 protein by a divergent central region. Assessment by PCR demonstrated that the gene encoding the M. avium 35-kDa protein was present in all 30 M. avium clinical isolates tested but absent from M. intracellulare, M. tuberculosis, or M. bovis BCG. Mice infected with M. avium, but not M. bovis BCG, developed specific immunoglobulin G antibodies to the 35-kDa protein, consistent with the observation that tuberculosis patients do not recognize the antigen. Strong delayed-type hypersensitivity was elicited by the protein in guinea pigs sensitized with M. avium.     

Differences in cell-mediated immune responses of 'high-resistance' and 'low-resistance' mice to a nonpathogenic mycobacterium

The kinetics of the footpad response of bacillus Calmette-Guérin (BCG)-infected mice to soluble BCG antigens were compared in two strains of mice with different degrees of susceptibility to Mycobacterium lepraemurium. For the first 21 days the responses of the 'high-resistance' C57BL and the 'low-resistance' BALB/c to the nonpathogenic BCG were similar to that produced when the pathogenic mycobacterium was used. After 4 weeks the kinetics of the BALB/c mice changed and resembled that of the C57BL mice. The change in kinetics was compared with circulating antimycobacterial antibody levels and the response of draining lymph node cells in the antigen-specific lymphocyte transformation test. A dissociation was found between the kinetics of the delayed footpad response and the lymphocyte transformation response. Since both strains of mice are equally resistant to BCG, it appears that the delayed footpad response cannot be used as an indicator of host resistance in all mycobacterial infections.     

Cross-reactivity of anti-10kD heat shock protein antibodies in leprosy and tuberculosis patients

The response to recombinant 10-kD heat shock protein (HSP) of Mycobacterium leprae (rML10) was evaluated by indirect ELISA in sera from leprosy patients, household contacts, tuberculosis patients and healthy controls in a leprosy-endemic area in the North East of Argentina. Some technical parameters were analyzed: within-assay and between-assay variability, dose-response curves and detectability indexes (specificity and sensitivity) of ELISA applied to measure anti-10 kDa antibodies. High levels of these antibodies have already been reported in positive bacilloscopy patients; herein we have also demonstrated that tuberculosis patients sera cross-react with this M. leprae antigen. This test seems to have a low sensitivity and specificity for leprosy detection; it confirms that antibodies against highly conserved HSP antigens are important in the polyclonal response against mycobacterial epitopes in leprosy as well as in tuberculosis.     

Does CDS have an open election? Chicago Dental Society

Sixty two and 59 patients with tuberculous and nontuberculous salpingo-oophoritis, respectively, and 30 healthy females were examined. It was found that indirect solid-phase enzyme immunoassay (EIA) using ultrasonography of Mycobacterium tuberculosis H37Rv could detect antituberculosis antibodies in 66.7% of patients with tuberculous salpingo-oophoritis, and in 10% of healthy females. That using the antigen isolated from the cell wall extract of M. tuberculosis (whose molecular weight was 38 - 42 kD) could reveal them in 70.2, 4.3%, and 6.7%, respectively. After dissociation of immune complexes, EIA inhibition using affinity-purified antimycobacterial antisera displayed mycobacterial antigens in 75.0 and 4.3% of patients with tuberculous and nontuberculous salpingo-oophoritis, respectively, and in none healthy female. Thus, the detection of mycobacterial antigens and antituberculosis antibody may be successfully used in the complex diagnosis of tuberculosis of the female genitals.     

Activation of human CD8+ alpha beta TCR+ cells by Mycobacterium tuberculosis via an alternate class I MHC antigen-processing pathway

Human immune responses to M. tuberculosis are characterized by activation of multiple T cell subsets including CD4+, CD8+, and gammadelta T cells, and the role of CD8+ alphabeta TCR+ T cells in this response is poorly understood. Stimulation of T cells from healthy tuberculin skin test-positive persons with live M. tuberculosis-H37Ra or soluble M. tuberculosis Ags readily up-regulated IL-2Ralpha (CD25) expression on CD8+ T cells. Purified resting and activated CD8+ T cells produced IFN-gamma and proliferated to both M. tuberculosis bacilli and soluble mycobacterial Ags with monocytes as APC. Precursor frequency of mycobacterial Ag-specific CD8+ T cells by IFN-gamma enzyme-linked immunospot was 5-10-fold lower than the precursor frequency of CD4+ T cells, and IFN-gamma secretion by CD8+ T cells was 50-100-fold lower. CD8+ T cells secreted approximately 10-fold less IFN-gamma per cell than CD4+ T cells in response to mycobacterial Ags. CD8+ T cell responses to M. tuberculosis bacilli were blocked by anti-MHC class I antibody and required Ag processing. Processing of M. tuberculosis bacilli by monocytes for presentation to MHC class I-restricted CD8+ T cells was insensitive to brefeldin A treatment, which blocks the conventional MHC class I Ag-processing pathway. These results represent the first demonstration that human cells can process pathogen Ags via an alternate Ag-processing pathway for MHC class I and suggest a mechanism for participation of IFN-gamma-secreting CD8+ T cells in the human immune responses to M. tuberculosis.     

A cis-regulatory element within the 5'' flanking region of arylsulfatase gene of sea urchin, Hemicentrotus pulcherrimus

Mycobacteria generally have thick cell walls and contain large amounts of lipid, making them resistant to DNA extraction. Five methods, namely, extensive enzymic digestion method (M1), 2-min mechanical glass-bead disruption method (M2), thermal shock method (M3), modified conventional enzymic digestion method (M4), and manual disruption with modified conventional enzymic digestion method (M5), were used to compare their effectiveness and simplicity in extracting DNA from slowly growing mycobacteria (Mycobacterium leprae, M. lepraemurium and M. bovis BCG), and a rapidly growing mycobacterium (M. phlei). The highest DNA yield was obtained by M2 from M. lepraemurium which produced 2.82 micrograms DNA/mg wet weight of cells, representing a theoretical yield of 78%. M3 gave the lowest DNA yield; 0.01 microgram DNA/mg wet weight of cells of M. lepraemurium was obtained. M4, in which proteinase K was used, is more effective than M1, in which subtilisin and pronase were used. M5 yielded a higher amount of DNA, but it required more manipulations to extract DNA as compared to M4. Extraction of DNA of M. leprae from nude mice is more difficult than that of M. leprae from armadillos by all of the methods used. These results suggest that the biosynthetic capabilities of these two forms of M. leprae may vary, depending on their cultural conditions and/or strain differences. Our results have shown that both M2 and M4 are the simplest, most effective and time-saving methods which are suitable for every routine laboratory to extract DNA from slowly and rapidly growing mycobacteria.     

Raised agalactosyl IgG and antimycobacterial humoral immunity in Takayasu's arteritis

OBJECTIVE: Takayasu's arteritis is an inflammatory occlusive disease of the aorta and its main branches of unknown etiology. Some suggested causes include inapparent infection with Mycobacterium tuberculosis, or autoimmunity evoked by this organism. We have therefore sought links with mycobacterial disease. METHODS: We assayed the % agalactosyl IgG, antibody to a tuberculosis-specific 38 kDa protein, and antibody to the mycobacterial 65 kDa heat shock protein (HSP), in patients with active or inactive Takayasu's arteritis, in whom the diagnosis of tuberculosis was excluded. The results were compared with findings in tuberculosis (positive controls), normal donors and patients with Wegener's granulomatosis. RESULTS: The % agalactosyl IgG in patients with active arteritis was in the range previously seen only in rheumatoid arthritis, Crohn's disease, and the mycobacterioses. Similarly, significantly raised antibody to the purified 38-kDa protein of M. tuberculosis, and to the 65-kDa HSP of M. leprae, was found in 78% of patients with Takayasu's arteritis, and the levels were higher in those with active disease. CONCLUSION: These results suggest that Takayasu's arteritis particularly clearly illustrates the occasional relationship between mycobacteria and diseases of superficially autoimmune pathogenesis.     

Analysis of cytokine production by Mycobacterium-reactive T cells. Failure to explain Mycobacterium leprae-specific nonresponsiveness of peripheral blood T cells from lepromatous leprosy patients

Recent analyses of antimycobacterial T cells clones from a small number of individuals indicate that mycobacteria preferentially induce Th cells that produce high levels of IFN-gamma and no or little IL-4 in Mycobacterium leprae-resistant tuberculoid leprosy (TT) patients and healthy subjects, whereas in one study M. leprae-induced Ts clones from polar lepromatous leprosy (LL) patients showed a reciprocal cytokine secretion profile and mediated their suppressive activity via the release of high levels of IL-4. We have evaluated these findings in peripheral blood T cells from a larger panel of TT and LL patients as well as healthy individuals. Mycobacterium-reactive T cell lines generated from the PBMC of these individuals were tested for cytokine secretion and proliferative capacity in response to M. leprae, Mycobacterium tuberculosis, and various individual mycobacterial Ag. The lepromatous pole of the leprosy spectrum was additionally investigated by analyzing the cytokine-secretion profile of M. leprae-induced (suppressor) T cell clones as well as primary ex vivo PBMC. All T cell lines from healthy individuals and TT patients responding to M. leprae, M. tuberculosis, or individual Ag, produced high levels of IFN-gamma and TNF-alpha but little or no IL-4 and IL-6. At the lepromatous pole, T cell lines failed to proliferate upon stimulation with M. leprae but in some cases produced significant levels of IFN-gamma. No IL-4 or IL-6 secretion was observed in response to M. leprae. These lines displayed strong proliferation and Th1-like cytokine production upon stimulation with M. tuberculosis. Similarly, stimulation of primary PBMC from LL patients with M. leprae or M. tuberculosis resulted in the release of IFN-gamma but no detectable IL-4 production. Control tetanus toxoid-reactive T cell lines from the same individuals instead produced large amounts of IL-4 and low levels of IFN-gamma. The analysis of M. leprae-induced T cell clones, including those with known suppressive activity, revealed that all lepromatous T cell clones produced large amounts of IFN-gamma. Most of these clones released no or little IL-4, but some clones produced higher levels of IL-4 in addition to IFN-gamma. Most clones tested produced IL-10 as well. The suppressor activity of suppressor T cell clones could not be inhibited by a neutralizing anti-IL-4 antibody and only in one case by neutralizing anti-IL-10 antibody. Anti-IL-4 and anti-IL-10 could not overcome the M. leprae-specific unresponsiveness observed in primary PBMC from LL patients.(ABSTRACT TRUNCATED AT 400 WORDS)