Expression of CD30 on T helper cells in the inflammatory infiltrate of acute atopic dermatitis but not of allergic contact dermatitis

The CD30 molecule has been proposed as a marker for a subset of CD4+CD45RO+ (memory) T cells with potent B cell helper activity producing IL-5 and IFN-gamma and as a specific marker for Th2 cells. Recently, an association has been demonstrated between elevated serum levels of soluble CD30, which is shed by CD30+ cells in vitro and in vivo, and atopic dermatitis but not respiratory atopic disorders or allergic contact dermatitis. We studied the expression of CD30 in the inflammatory infiltrate of atopic dermatitis compared with that of allergic contact dermatitis, with special regard to skin disease activity (acute vs subacute/ chronic). Biopsies were obtained from 16 patients suffering from atopic dermatitis (acute n = 6, subacute/ chronic n = 10), from 7 patients with acute allergic contact dermatitis and from 5 positive patch-test reactions. Paraffin-embedded as well as snap-frozen material was stained with anti-CD30 and anti-CD45RO mAbs according to standard procedures. Double-staining procedures for CD30CD3, CD30CD4, CD30CD45RO and CD30CD68 were also performed. Abundant CD45RO+ cells were detected both in atopic dermatitis and in allergic contact dermatitis lesions. We found scattered CD30+ cells in only one of six formalin-fixed paraffin-embedded acute atopic dermatitis biopsies, but in all of the respective snap-frozen specimens, possibly because CD30 expression on atopic dermatitis infiltrating cells is weak and sensitive to formalin fixation and paraffin embedding. CD30CD3 and CD30CD4 double staining identified CD30+ cells to be helper T lymphocytes. No significant CD30 expression (either in paraffin-embedded or in frozen material) could be found in subacute/chronic atopic dermatitis lesions or in any of the specimens of allergic contact dermatitis. The results suggest a specific regulatory function of CD30+ T cells in acute atopic dermatitis. With respect to the view that CD30 is a marker for Th2 cells, our observations confirm previous findings that Th2 cells predominate in the infiltrate particularly of acute atopic dermatitis. CD30 expression in acute atopic dermatitis but not in acute allergic contact dermatitis might be helpful in the histological differentiation of these disorders and in the further characterization of atopy patch testing.     

Allergen specificity of skin-infiltrating T cells is not restricted to a type-2 cytokine pattern in chronic skin lesions of atopic dermatitis

The majority of allergen-specific T cells derived from inhalant allergen patch test lesions in patients with atopic dermatitis were previously found to produce a restricted type-2 cytokine pattern. Recent studies, however, have revealed that in chronic eczematous skin lesions of patients with atopic dermatitis, expression of the type-1 cytokine interferon-gamma predominates. To evaluate cytokine production by allergen-specific T cells in chronic atopic dermatitis, we established house dust mite (Dermatophagoides pteronyssinus)-specific T-cell clones from the dermis of chronic skin lesions of sensitized adult patients with atopic dermatitis. Frequencies of skin-derived T cells proliferating in the presence of Dermatophagoides pteronyssinus were between one in 138 and one in 4255, indicating that only a minority of skin-infiltrating T cells are allergen specific. When these cells were analyzed for their capacity to produce interferon-gamma, the majority (71%) of these cells were found to express interferon-gamma mRNA and to secrete interferon-gamma protein, either alone or in combination with interleukin-4. Phenotypic analysis revealed that 15% of skin-infiltrating allergen-specific T cells were CD8+. No selection of Vbeta elements was detected in Dermatophagoides pteronyssinus-specific T-cell clones. These studies demonstrate that allergen specificity of skin-infiltrating T cells is not restricted to a type-2 cytokine pattern in lesional atopic dermatitis. The notion that the majority of allergen-specific, skin-infiltrating T cells are capable of producing interferon-gamma further supports the concept that interferon-gamma expression has major pathogenetic relevance for the chronic phase of atopic dermatitis.     

Circulating skin-homing T cells in atopic dermatitis. Selective up-regulation of HLA-DR, interleukin-2R, and CD30 and decrease after combined UV-A and UV-B phototherapy

BACKGROUND: As the cutaneous lymphocyte-associated antigen appears to detect circulating T cells that migrate to the skin in atopic dermatitis but not T cells that migrate to mucosal sites in allergic asthma and rhinitis, we investigated T-cell activation markers and CD30 on the cutaneous lymphocyte-associated antigen-positive circulating T-cell subset in atopic dermatitis to see whether these markers are different from those in normal controls and related to disease activity. DESIGN: Open study. SETTING: University referral center. PATIENTS: Twelve patients with atopic dermatitis and 12 healthy controls. INTERVENTION: Combined UV-A and UV-B treatment for 2 months. MAIN OUTCOMES MEASURES: Percentage of circulating cutaneous lymphocyte-associated antigen-positive T cells that express HLA-DR, interleukin-2 receptor, CD69, CD71, and CD30 (triple-color flow cytometric analysis). Clinical score, Dermatology Life Quality Index, pruritus score, and consumption of topical corticosteroids were determined. RESULTS: Increased relative numbers of cutaneous lymphocyte-associated antigen-positive T cells expressing HLA-DR, interleukin-2 receptor, and CD30 were found in patients with atopic dermatitis before treatment. Treatment with UV-A and UV-B was associated with clinical improvement and a decrease of levels of HLA-DR, interleukin-2 receptor, and CD30 in cutaneous lymphocyte-associated antigen-positive T cells. HLA-DR on cutaneous lymphocyte-associated antigen-positive T cells correlated significantly with the clinical score. CONCLUSION: Expression of HLA-DR and interleukin-2 receptor is a sensitive marker of disease activity in atopic dermatitis. Apart from giving information on disease activity in atopic dermatitis, the availability of skin-seeking T cells in the blood offers the opportunity to obtain further information on T cells that may have effector function in the skin.     

Immunophenotyping of skin-infiltrating T-cell subsets in dogs with atopic dermatitis

Atopic dermatitis in dogs has many clinical features that are identical to those of the same disorder in man. To investigate the pathogenesis of this disease in dogs and the possibility of similarities to the pathogenesis in humans we compared the presence and ratio of CD4+ and CD8+ T-cells in the cutaneous infiltrate of lesional and non-lesional skin of atopic dogs with that in the skin of healthy dogs. In ten dogs with atopic dermatitis and ten healthy dogs the skin was biopsied at the predilection sites for atopic dermatitis and histological sections were immunohistochemically stained for CD4 and CD8. The staining showed an increase in CD4+ and CD8+ T-cells in canine lesional atopic skin, with a predominance of CD4+ T-cells in the epidermis. In non-lesional atopic skin there was also an infiltration with CD4+ and CD8+ T-cells, but without predominance of CD4+ T-cells. The results in the separate predilection sites did not differ substantially from the mean results. These observations indicate further similarities in the immunopathogenesis of atopic dermatitis in dogs and humans, which may have consequences for the control of atopic dermatitis in dogs and contributes to a possible role of the dog as a model for human atopic dermatitis.     

In vivo relevance of CD30 in atopic dermatitis

CD30 expression was evaluated by immunohistochemistry in lesional skin biopsies of eight patients with active atopic dermatitis (AD) and three patients with allergic contact (nickel-induced) dermatitis (ACD). CD30 expression was also assessed in a large panel of CD4+ and CD8+ T-cell clones generated from the skin biopsies of four patients with AD. Finally, the levels of soluble CD30 (sCD30) were measured in the serum of 41 patients with AD, 19 patients with ACD, and 60 healthy controls. In all specimens of lesional AD skin, where the great majority of infiltrating cells were CD4+ T cells, remarkable numbers of cells were CD30+, whereas virtually no CD30+ cells were found in the skin of patients with ACD. In CD4+ T-cell clones generated from the lesional AD skin, most of which produced both interleukin (IL)-4 and interferon-gamma (IFN-gamma) (Th0-like cells) or IL-4 and IL-5, but not IFN-gamma (Th2-like cells), CD30 expression directly correlated with the ability to produce IL-4 and IL-5, but was inversely related to IFN-gamma production. High levels of sCD30 (correlated with disease activity: r = 0.618) were detected in the serum of most AD patients, whereas there was no increase of sCD30 levels in the serum of patients with ACD. These data support the view that Th0/Th2-type responses predominate in the skin of patients with AD and suggest that the presence of CD30+ T cells in tissues and/or increased levels of sCD30 in biologic fluids are indicative of Th2-dominated responses.     

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Eosinophil differentiation is thought to occur by the action of interleukin (IL)-5 on CD34(+) progenitor cells. The allergen-induced increase in eosinophil numbers in isolated airway preparations in vitro, and detection of increased numbers of circulating CD34(+) cells in atopic subjects, led us to the hypothesis that the eosinophil infiltration of the airway in asthma may result from local mucosal differentiation, in addition to recruitment from the bone marrow. We examined CD34(+) cell numbers by immunohistochemistry and IL-5 receptor alpha (IL-5Ralpha) messenger RNA (mRNA) expression by in situ hybridization in bronchial biopsies from atopic asthmatic patients, and from atopic and nonatopic control subjects. CD34(+) cell numbers were increased in the airway in atopic asthmatic and atopic nonasthmatic subjects. In contrast, CD34(+)/ IL-5Ralpha mRNA+ cells were increased in asthmatic subjects when compared with both atopic and nonatopic control subjects. Airway numbers of CD34(+)/IL-5Ralpha mRNA+ cells were correlated to airway caliber in asthmatic subjects and to eosinophil numbers. These findings support the concept that eosinophils may differentiate locally in the airway in asthma.     

Role of Mitf in differentiation and transdifferentiation of chicken pigmented epithelial cell

A recombinant H-2Kb transgene, GK, containing the human HLA-G gene promoter is expressed throughout the trophoblast when inherited paternally. Male GK transgenic mice were mated with female T-cell receptor (TCR) transgenic mice to assess the effect of fetal H-2Kb expression on maternal H-2Kb-specific CD8+ T-cells during pregnancy. The number of maternal H-2Kb-specific CD8+ T-cells in spleen increased significantly (approximately 3-fold) 10 days post coitus when the GK transgene was inherited from the father. A smaller (approximately 2-fold) increase was observed in the spleen of pregnant females mated with C57BL/10 (H-2b) males. No increase was observed in mothers mated to syngeneic male mice. In both cases where expanded cohorts of maternal CD8+ T-cells were observed the amount of surface CD8 and to a lesser extent, TCR molecules was reduced. No change in the amount of surface CD44 or CD45RB was detected when levels were compared with naive T-cells from control virgin female mice. Expanded cohorts of CD8+ T-cells were also detected in para-aortic and inguinal lymph nodes draining the uterus but no changes were observed in mesenteric lymph nodes. This study concludes that maternal CD8+ T-cells are exposed to paternally inherited fetal MHC class I antigens during pregnancy. Moreover, the phenotype of the CD8+ T-cells in maternal spleen and lymph nodes that drain the uterus is not typical of activated, antigen-experienced T-cells suggesting that contact with fetal H-2Kb molecules induces a state of functional unresponsiveness.     

Gamma interferon administration to patients with atopic dermatitis inhibits fibrinolysis and elevates C1 inhibitor

Recombinant human gamma interferon was used to treat 10 atopic dermatitis patients. Recombinant gamma interferon was administered weekly for three consecutive days at 50 microg/M2 SQ for four weeks. All patients' dermatitis improved with recombinant gamma interferon therapy and plasma tumor necrosis factor-alpha levels rose with treatment. Recombinant gamma interferon treatment positively correlated with reduced total plasma fibrinolysis as measured by the fibrin lysis plate, plasmin-alpha2antiplasmin complexes, and tissue type plasminogen activator levels. Accordingly, plasminogen activator inhibitor levels increased. Treatment also was associated with a transient increase in thrombin-antithrombin III complexes. Recombinant gamma interferon resulted in a significant increase in C1 inhibitor antigen but not activity. Plasma prekallikrein, high molecular weight kininogen, and factor XII levels were not decreased. However, 5 of the 10 atopic dermatitis patients before therapy had circulating cleaved plasma high molecular weight kininogen detected on immunoblot, indicating prior kallikrein formation. The cleaved, circulating plasma high molecular weight kininogen disappeared in four out of the five original patients who were reexamined at one year after treatment. These combined data indicated that recombinant gamma interferon treatment reduced total plasma fibrinolysis. In untreated atopic dermatitis, circulating cleaved high molecular weight kininogen also may be a presenting manifestation.     

Investigations of the cellular immunity during depression and the free interval: evidence for an immune activation in affective psychosis

1. Results of investigations of the immune function in affective disorders are conflicting. Some authors described an immune suppression, others an immune activation in major depression. The authors performed a study of cellular immunity in the MDD subtype endogenous depression. 23 patients suffering from endogenous depression were investigated during the depressive state, the results were compared with a group of 14 patients during the free interval and 51 healthy controls. 2. The lymphocyte proliferation after incubation with diphtheria- and tetanus toxoid, mainly stimulating T-cells, was reduced but after incubation with an antigen-cocktail, stimulating both, T- and B-cells, was increased in patients during depression and during the free interval compared to controls. 3. The CD3(+)- and CD4(+)-cells were significantly enhanced in both groups of patients while the CD8(+)-cells showed no differences to the controls. The ratio CD4+/CD8+ was increased in patients, too, as described in some autoimmune disorders. 4. The suppressor cell activity was significantly reduced in the PWM-assay and in the PHA-assay. The mixed lymphocyte culture showed a tendency to reduced suppressor cell activity as well. 5. The results point to an immune activation and to a disturbed control of the proliferative activity in affective psychosis. A T-cell related defect, not compensated by an increased number of CD3+- and CD4+ -cells is discussed. 6. From our point of view, the conflicting results of psychoneuroimmunological investigations in depressive disorders may be related to etiologically different subgroups of depression. The diagnostic category of MDD is possibly one of the traps in psychoneuroimmunology.     

T cells subsets and cytokines in allergic and non-allergic children. II. Analysis and IL-5 and IL-10 mRNA expression and protein production

Interleukin 5 (IL-5) has an enhancing effect on IL-4 induced immunoglobulin E (IgE) synthesis. Furthermore, IL-5 plays an important role in the differentiation, recruitment, activation and survival of eosinophils. IL-10 has a downmodulating effect on interferon gamma (IFN-gamma) production and can exert strong anti-inflammatory activities. Therefore, we analysed whether differences were present in IL-5 and IL-10 mRNA expression and protein production between T cells of children with allergic and non-allergic asthma, atopic dermatitis and healthy control children. We demonstrated significant increases in IL-5 mRNA expression and protein production in different T cell fractions of children with allergic and non-allergic asthma and children with atopic dermatitis as compared to healthy controls. This indicates that IL-5 is not only involved in allergy, but also plays a role in the inflammatory process of non-allergic asthma. Interestingly, IL-10 mRNA expression by purified T cells of children with allergic and non-allergic asthma and children with atopic dermatitis was strongly decreased as compared with that of healthy controls. In the peripheral blood mononuclear cell (PBMC) fraction, IL-10 mRNA expression was comparable between the four groups. We hypothesize that this decreased T cell derived IL-10 expression results in a lack of immunosuppression of the inflammatory process in these diseases. However, a role of monocyte derived IL-10 cannot be ruled out.     

Expression of the activation antigen CD27 in rheumatoid arthritis

Differentiation of CD4+ T-cells is reflected by the change from the CD45RA+CD27+ phenotype via CD45RO+CD27+ to the CD45RO+CD27- phenotype. To provide insight into the migration and activation of T-cells at the site of inflammation in rheumatoid arthritis (RA), CD27 expression by T-cells in peripheral blood (PB), synovial fluid (SF), and synovial tissue (ST) as well as the levels of the soluble form of CD27 (sCD27) in plasma and SF were studied in patients with RA. Since CD4+CD27+ T-cells are involved in providing helper activity for B-cells, we also investigated the levels of rheumatoid factors in serum and SF in relation to CD27 expression. The mean level of sCD27, which is produced by CD27+ cells, and the mean percentage of CD27 T-cells within the CD4+CD45RA- subset were higher in SF than in PB. SF sCD27 levels were higher in the patients with RA than in the patients with osteoarthritis, who served as controls. In ST infiltration by CD4+CD45RO+CD27+ T-cells, could be demonstrated in the rheumatoid perivascular lymphocytic aggregates with a relative increase in the percentage of CD27- T-cells in the diffuse lymphocytic infiltrate. The sCD27 levels and the percentages of CD4+CD27+ cells in SF correlated positively with the levels of rheumatoid factors in serum and SF. The findings presented in this study suggest a continuous influx of preactivated CD4+CD45RO+CD27+ cells from the PB into the rheumatoid ST and further activation and differentiation to CD4+CD45RO+CD27- cells in situ, followed by migration to the SF. These activated T-cells are likely to play a role in synovial inflammation.     

Membrane localisation of a UDP-sugar hydrolase, in Salmonella, is by an uncleaved N-terminal signal peptide

Many immunologic aspects of atopic dermatitis have been studied, but basic pathobiologic mechanisms of this disease remain unknown. In this study, we measured the production of interleukin-6 (IL-6) by peripheral blood T cells and monocytes from patients with atopic dermatitis in comparison to normal control subjects and patients with chronic psoriasis. We found that peripheral blood T cells isolated from patients with atopic dermatitis produced significantly higher levels of IL-6 (36.1 +/- 5.1 units/ml, n = 22) than T cells derived from either normal subjects (12.6 +/- 1.9 units/ml, n = 22) or patients with chronic psoriasis (26.7 +/- 4.1 units/ml, n = 7). T-cell activation was also measured in the patients with atopic dermatitis by soluble serum IL-2 receptor levels and were found to be significantly higher (623.7 +/- 8.1 units/ml, n = 8) than normal subjects (357.2 +/- 26.0 units/ml, n = 8). In contrast to the increased production of IL-6 by T cells in atopic dermatitis, there was no significant difference in the IL-6 production by peripheral blood monocytes derived from patients with atopic dermatitis compared to normal subjects. Thus, peripheral blood T cells derived from patients with AD spontaneously produce increased amounts of IL-6 compared to T cells from normal subjects, which may reflect the increased activation state of T cells in atopic dermatitis. These data support the concept that activated T cells or subsets of T cells may be important effector cells in mediating inflammatory activity in atopic disease.     

CD30 ligand is frequently expressed in human hematopoietic malignancies of myeloid and lymphoid origin

CD30 ligand (CD30L) is a type-II membrane glycoprotein capable of transducing signals leading to either cell death or proliferation through its specific counterstructure CD30. Although several lines of evidence indicate that CD30L plays a key role as a paracrine- or autocrine-acting surface molecule in the deregulated cytokine cascade of Hodgkin's disease, little is known regarding its distribution and biologic significance in other human hematopoietic malignancies. By analyzing tumor cells from 181 patients with RNA studies and immunostaining by the anti-CD30L monoclonal antibody M80, we were able to show that human hematopoietic malignancies of different lineage and maturation stage display a frequent and broad expression of the ligand. CD30L mRNA and surface protein were detected in 60% of acute myeloid leukemias (AMLs), 54% of B-lineage acute lymphoblastic leukemias (ALLs), and in a consistent fraction (68%) of B-cell lymphoproliferative disorders. In this latter group, hairy cell leukemia and high-grade B-cell non-Hodgkin's lymphoma (B-NHL) expressed a higher surface density of CD30L as compared with B-cell chronic lymphocytic leukemia and low-grade B-NHL. Purified plasmacells from a fraction of multiple myeloma patients also displayed CD30L mRNA and protein. A more restricted expression of CD30L was found in T-cell tumors that was mainly confined to neoplasms with an activated peripheral T-cell phenotype, such as T-cell prolymphocytic leukemia, peripheral T-NHL, and adult T-cell leukemia/lymphoma. In contrast, none of the T-lineage ALLs analyzed expressed the ligand. In AML, a high cellular density of CD30L was detected in French-American-British M3, M4, and M5 phenotypes, which are directly associated with the presence on tumor cells of certain surface structures, including the p55 interleukin-2 receptor alpha-chain, the alpha(M) (CD11b) chain of beta2 integrins, and the intercellular adhesion molecule-1 (CD54). Analysis of normal hematopoietic cells evidenced that, in addition to circulating and tonsil B cells, a fraction of bone marrow myeloid precursors, erythroblasts, and subsets of megakaryocytes also express CD30L. Finally, we have shown that native CD30L expressed on primary leukemic cells is functionally active by triggering both mitogenic and antiproliferative signals on CD30+ target cells. As opposed to CD30L, only 10 of 181 primary tumors expressed CD30 mRNA or protein, rendering therefore unlikely a CD30-CD30L autocrine loop in human hematopoietic neoplasms. Taken together, our data indicate that CD30L is widely expressed from early to late stages of human hematopoiesis and suggest a regulatory role for this molecule in the interactions of normal and malignant hematopoietic cells with CD30+ immune effectors and/or microenvironmental accessory cells.     

The role of mucosal biopsy in the diagnosis of chronic diarrhea: value of multiple biopsies when colonoscopic finding is normal or nonspecific

The CTLA4 receptor is a CD28 homologue which induces inhibitory effect on activated T-cells. Peripheral T-cells proliferate spontaneously in CTLA4-deficient mice. These results led to an analysis of CTLA4 expression in human lymphomas (n = 82) including Hodgkin's disease (HD) and non-Hodgkin's lymphomas (NHLs), using immunohistochemistry. CTLA4 was present in neoplastic cells from most (10/11) T-cell malignancies, except for anaplastic and lymphoblastic subtypes (0/4). Malignant B-cells from rare (3/55) B-NHLs (all of follicular subtype) were also CTLA4-positive. Other B-NHLs (52/55) were negative in malignant B-cells and occasionally positive in T-cells. Reactive small lymphocytes, but not Reed-Sternberg cells, from all (12/12) HD cases were strongly CTLA4-positive. The CTLA4 ligands CD80 and CD86 were simultaneously expressed in most CTLA4-negative lymphoma cases. CTLA4 is thus expressed either in the reactive or in the malignant cell populations, depending on the lymphoma subtype. These results provide new insights leading towards therapeutic strategies based either on enhancement of anti-tumour immunity by CTLA4 blockade in reactive lymphocytes or on triggering of a CTLA4-mediated inhibitory pathway in lymphoma cells.     

The characteristics of the development of the immune function in the transplanted spleen of newborn mouse pups in recipients of different ages. 2. The effect of the thymus on the functional development of the transplant]

The effect of the neonatal thymus grafting or "Thymostimulin" administration on the cellularity, cell composition, immune, response to SRBC and proliferative activity of T- and B-cells in vitro were determined in neonatal spleen grafted CBA/Ca female mice of different ages. Analysis of the thymus graft effect on the T- and B-cells content in the spleen transplant from the adult and old recipients demonstrated no differences. The neonatal thymus grafting led to the essential increase of the immune response, spleen cellularity and to the diametrically opposed changing from negative to positive of the sign of the correlation coefficient between the T-cells content and the cellularity of the neonatal spleen in the old recipients. The similar effect of the neonatal thymus grafting was revealed in respect of correlative connection between content of the T-cells and PFCs in spleen grafted to the old recipients too. The "Thymostimulin" injection led only to the increase of the spleen transplant cellularity. These results suggests that the young thymic microenvironment is essential for the normal T-cells differentiation and for its normal function in the neonatal spleen transplant.     

Two distinct pathways of interleukin-5 synthesis in allergen-specific human T-cell clones are suppressed by glucocorticoids

Glucocorticoids (GC) have long been used as the most effective agents for the treatment of allergic diseases accompanied by eosinophilia such as chronic asthma and atopic dermatitis. The development of chronic eosinophilic inflammation is dependent on interleukin-5 (IL-5), a selective eosinophil-activating factor, produced by helper T cells. To delineate the regulatory mechanisms of human IL-5 synthesis, we established allergen-specific CD4+ T-cell clones from asthmatic patients. GC efficiently suppressed IL-5 synthesis of T-cell clones activated via either T-cell receptor (TCR) or IL-2 receptor (IL-2R). Induction of IL-5 mRNA upon TCR and IL-2R stimulation was totally inhibited by dexamethasone. Human IL-5 promoter/enhancer-luciferase gene construct transfected to T-cell clones was transcribed on either TCR or IL-2R stimulation and was clearly downregulated by dexamethasone, indicating that the approximately 500-bp human IL-5 gene segment located 5' upstream of the coding region contains activation-inducible enhancer elements responsible for the regulation by GC. Electrophoretic mobility shift assay analysis suggested that AP-1 and NF-kappaB are among the possible targets of GC actions on TCR-stimulated T cells. NF-AT and NF-kappaB were not significantly induced by IL-2 stimulation. Our results showing that GC suppressed IL-5 production by human CD4+ T cells activated by two distinct stimuli, TCR and IL-2R stimulation, underscore the efficacy of GC in the treatment of allergic diseases via suppression of T-cell IL-5 synthesis.     

Prognosis of the skin UV-incidence increase in Poland

We studied the morphologic and immunohistochemical features of 10 peripheral T-cell lymphomas of a cytotoxic phenotype (CD3+/CD4-/CD8+), encountered among 98 peripheral T-cell lymphomas (PTCLs). Nine tumors were positive for both cytotoxic molecules, namely perforin (Pf) and granzyme B (GrB), and strong positivity was seen in the majority of the malignant cells. We also studied the expression of these molecules in 92 other cases of T-cell and natural killer (NK) cell neoplasms; 18 anaplastic large cell lymphomas (ALCLs); 63 CD4+ PTCLs; 10 CD56+ nasal lymphomas; and 1 NK-cell leukemia. Most of the CD4+ PTCLs (62 of 63) were negative for GrB, but all of the nasal lymphomas and the NK cell leukemia were positive for both Pf and GrB. Variable expression was seen among the 18 ALCLs. Within the 10 CD8+ PTCLs, 4 involved the skin, 3 of which were diagnosed as primary cutaneous lymphomas. Five patients died within 1 year of diagnosis. According to the Revised European-American Classification of Lymphoid Neoplasms, seven cases were categorized as "PTCL, unspecified," and three as "angioimmunoblastic T-cell lymphoma," "adult T-cell lymphoma/leukemia," or "small cell lymphoma," respectively. Three cases had characteristic morphologic features consisting of large lymphomatous cells with massive necrosis and nuclear fragmentation. Epstein-Barr virus mRNA was detected by in situ hybridization in three cases. Although the degree of apoptosis varied, apoptotic cells were detected in all cases by terminal deoxynucleotidyl transferase-mediated deoxyuridine 5-triphosphate-biotin nick end labeling. We conclude that CD8+ PTCLs are relatively rare, often involve extranodal sites, have an aggressive clinical course, and are often associated with Epstein-Barr virus. Compared with ALCLs, which have recently been considered as neoplasms of cytotoxic T-cells, we think that CD8+ PTCLs are more lineage-specific neoplasms of mature, cytotoxic, T lymphocytes.     

The Fas antigen and Fas-mediated apoptosis in B-cell differentiation

In the B-cell lineage, Fas, a type 1 membrane protein belonging to the tumor necrosis factor receptor (TNF) family, is expressed on B-cells at a restricted developmental stage and on activated B-cells, but not on naive mature B-cells. Apoptosis mediated by Fas-Fas ligand interactions may be involved in the peripheral elimination of autoreactive B-cells and in the regulation of the immune response through deletion of B-cells activated by foreign antigens, as for the T-cell lineage. Fas-mediated apoptosis associated with B-cell activation is affected by costimulation through other accessory signaling molecules like CD40, whose ligands are on T-cells.