Defective suppression of Th2 cytokines by CD4+CD25+ regulatory T cells in birch allergics during birch pollen season

BACKGROUND: CD4(+)CD25+ regulatory T cells suppress proliferation and cytokine production by human T cells both to self-antigens and exogenous antigens. Absence of these cells in human newborns leads to multiple autoimmune and inflammatory disorders together with elevated IgE levels. However, their role in human allergic disease is still unclear. OBJECTIVE: This study aimed to evaluate the capacity of CD4(+)CD25+ regulatory T cells to suppress proliferation and cytokine production outside and during birch-pollen season in birch-allergic patients relative to non-allergic controls. METHODS: CD4+ cells were obtained from blood of 13 birch-allergic patients and six non-allergic controls outside pollen season and from 10 birch-allergic patients and 10 non-allergic controls during birch-pollen season. CD25+ and CD25- fractions were purified with magnetic beads and cell fractions, alone or together in various ratios, were cultured with antigen-presenting cells and birch-pollen extract or anti-CD3 antibody. Proliferation and levels of IFN-gamma, IL-13, IL-5 and IL-10 were measured by thymidin incorporation and ELISA, respectively. Numbers of CD25+ cells were analysed by flow cytometry. RESULTS: CD4(+)CD25+ regulatory T cells from both allergics and non-allergics potently suppressed T cell proliferation to birch allergen both outside and during birch-pollen season. However, during season CD4(+)CD25+ regulatory T cells from allergic patients but not from non-allergic controls were defective in down-regulating birch pollen induced IL-13 and IL-5 production, while their capacity to suppress IFN-gamma production was retained. In contrast, outside pollen season the regulatory cells of both allergics and non-allergic controls were able to inhibit T-helper 2 cytokine production. CONCLUSION: This is the first study to show differential suppression of Th1 and Th2 cytokines, with CD4(+)CD25+ regulatory T cells from birch-pollen-allergic patients being unable to down-regulate Th2, but not Th1 responses during birch-pollen season.     

Spindle cell lipoma in an intramuscular lipoma

Intramuscular lipoma (IML) is a relatively common variant of lipomas. The most important sites for IML are the large muscles of the extremities. Spindle cell lipoma (SCL) is a rare and distinct variant of lipoma. Most SCL arise in the neck, shoulders or back. It has also been described in unusual sites, such as the oral cavity, larynx, bronchus, breast, orbit and extremities. However, localization of a SCL in an IML has not been described yet. Thus, we present the first SCL located in an IML, which was localized underneath the fascia and embedded within the left sartorius muscle of a 55-year-old man. Microscopically, the SCL component of the tumor was sharply circumscribed by a fibrous capsule and clearly separated from the IML in which it was localized. The collagen-forming spindle cells of the SCL showed neither atypia nor pleomorphism. These cells stained positive for CD34, while the mature fat tissue component of the SCL was positive for S-100 protein and negative for CD34. Spindle cells were negative for S-100 protein. Vimentin stained both components of the SCL, as well as the striated muscle fibers and mature fat tissue of the IML. In conclusion, careful morphological observation along with immunohistochemistry for CD34 and S-100 protein are essential to differentiate this rare tumor from lesions that enter the differential diagnosis.     

The pattern and frequency of t(14;18) translocation and immunophenotype in Asian follicular lymphoma

AIMS: Follicular lymphoma is frequently associated with t(14;18)(q32;q21) translocation. This study was undertaken to determine the pattern of Bcl-2, CD10 and Bcl-6 expression in relation to t(14;18) translocation in follicular lymphoma from a cohort of a multi-ethnic Asian population. METHODS AND RESULTS: Sixty-two cases of follicular lymphoma were retrieved for immunohistochemistry, and t(14;18) translocation analysis by polymerase chain reaction and fluorescent in-situ hybridization techniques. Bcl-2 expression was present in 74% of the cases. CD10 expression was also relatively low (61%), with decreasing frequency of expression in high-grade tumours. Bcl-6 protein was expressed in most of the tumours (88%) regardless of the tumour grade. The t(14;18) translocation was detected in 46 cases (74%) with an extremely high rate of t(14;18) translocation in ethnic Indian cases (100%). CONCLUSION: The frequency of t(14;18) translocation in this series of follicular lymphomas was higher when compared with previous Asian reports, but in accordance with European and North American findings. CD10 expression is strongly associated with a t(14;18) translocation event, but the overall CD10 expression was relatively low, possibly due to the high proportion of high-grade tumours in the series. t(14;18) translocation was not associated with Bcl-2 or Bcl-6 expression.     

Identification and characterization of macaque CD89 (immunoglobulin A Fc receptor)

The interaction of the immunoglobulin A (IgA) molecule with its specific cellular receptor is necessary to trigger a variety of effector functions able to clear IgA-opsonized antigens. The human IgA-specific Fc receptor, FcalphaRI or CD89, is expressed on cells of the myeloid lineage. Recently, CD89 homologues have been identified in rats and cattle. Because non-human primates represent well established models for a variety of human diseases and for the testing of immunotherapeutic strategies, we cloned and sequenced cDNAs corresponding to the CD89 gene from rhesus (Macaca mulatta) and cynomolgus (Macaca fascicularis) macaques. Macaque sequences of full-length CD89 consist of five exons of length identical to the corresponding human CD89 exons. The rhesus and cynomolgus macaque derived amino acid sequences are highly homologous to each other (99.3% identity) and exhibit 86.5% and 86.1% identity to the human counterpart, respectively. Transfection of HeLa cells with plasmids containing the cloned macaque cDNAs resulted in the expression of surface molecules recognized by an anti-human CD89 antibody. Five splice variants were identified in rhesus macaques. Three of the five variants are similar to described human CD89 splice variants, whereas two variants have not been described in humans. Three splice variants were identified in cynomolgus macaques. Of the three variants, one is present also in humans and rhesus macaques, whereas the other two are shared with rhesus macaques but not humans. Similarly to the human CD89, macaque CD89 is expressed on myeloid cells from peripheral blood. The characterization of macaque CD89 represents an essential step in establishing a non-human primate model for the testing of immunotherapeutic approaches based on the manipulation of the IgA/CD89 interaction.     

Interleukin-10 (IL-10) secretion in systemic lupus erythematosus and rheumatoid arthritis: IL-10-dependent CD4+CD45RO+ T cell-B cell antibody synthesis

Interleukin-10 (IL-10) is a major immunoregulatory cytokine and has a multitude of immunomodulatory effects in the immune system. In this study, we have examined the secretion andin vitro function of IL-10 in B cell hyperactivity in antibody production in two common autoimmune diseases, systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). IL-10 was detectable in serum of all active SLE and serum and synovial fluid samples of all RA patients but in none of the normal controls. B cells and CD4+CD45RO+ memory T cells secreted highly enhanced levels of IL-10 in SLE and RA versus normals. Increased IgM and IgG production by B cells-CD4+CD45RO+ T cells in SLE and RA was IL-10 dependent, since neutralization of IL-10 cytokine by anti-IL-10 antibody drastically reduced Ig synthesis in these coculture experiments. B cell hyperactivity in autoantibody production in SLE and RA may be a function of IL-10-dependent CD4+CD45RO+ Th2 cell activation. Therefore, IL-10 may play an important role in highly disturbed immune system and B cell-T cell function in these immune disorders.     

Expression of E-selectin, intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 in non-small-cell lung carcinoma

Vascular cell adhesion molecules (VCAM) play an important part in the regulation of inflammation and are considered to be important in the process of malignant tumour growth. The present study describes the immunohistochemical staining patterns of E-selectin, intercellular adhesion molecule (ICAM)-1 and VCAM-1 on endothelial cells of the vessels in tumour stroma and other cell types in non-small-cell lung carcinoma (NSCLC; n=43) in association with inflammatory cells. Expression of E-selectin was dominant on endothelial cells in the stromal areas of the tumour, especially at the borders, and was confined to endothelial cells. Moderate to strong staining for ICAM-1 was demonstrated on endothelial cells irrespective of size or localization of the vessels. Compared with ICAM-1, fewer vessels were positive for VCAM-1, and stained with lesser intensity. ICAM-1 expression was demonstrated on NSCLC cells, the basal cells of bronchial epithelium, type II pneumocytes, lymphocytes and fibroblasts. VCAM-1 was clearly expressed on NSCLC cells in 4 of the 43 cases and on lymphocytes and fibroblasts. The staining patterns observed on endothelial cells support the idea of an active status of NSCLC vessels. This phenotypic pattern looks similar to the vascular component of inflammation. The presence of ICAM-1 and VCAM-1 on NSCLC cells suggests a functional role in the process of chemotaxis for tumour cells.     

Superantigen responses and co-stimulation: CD28 and CTLA-4 have opposing effects on T cell expansion in vitro and in vivo

Co-stimulation via the CD28/CTLA-4 system appears critical forT cell proliferation to peptide antigens presented in associationwith MHC. In this study, we examine the roles of CD28 and CTLA-4in the response of murine T cells to the superantigen staphylococcalenterotoxin B (SEB). In vitro, antibodies against B7-1/B7-2or Fab fragments of anti-CD28 antibodies significantly inhibitthe response of splenocytes to SEB. Conversely, Fab fragmentsof anti-CTLA-4 antibodies augment the proliferative response.Further, addition of blocking antibodies directed against B7-1/B7-2augment proliferation co-stimulated by intact anti-CD28 antibodies.These data support the hypothesis that CD28 and CTLA-4 exertopposing effects upon early T cell activation. In vivo, Intactanti-CD28 antibodies and non-stimulatory Fab fragments of anti-CD28appear to have similar inhibitory effects upon the expansionof V_ß8⁺ T cells. In contrast, both intact and Fabfragments of anti-CTLA-4 appear to amplify this expansion. Weconclude that the SEB response is significantly augmented byCD28-derived signaling and this in turn may be attenuated bysignals through CTLA-4.     

Elevation of plasma thioredoxin levels in HIV-infected individuals

Thioredoxin (Trx), a ubiquitous protein intimately involvedin redox and protein disulfide reductions, has been shown tobe released from cells and to have cytokine-like activities.In addition, Trx has been implicated in the redox regulationof immunological responses and shown to be deficient in tissuesfrom AIDS patients. In studies presented here, plasma Trx levelswere measured by ELISA in plasma samples from HIV-infected individuals(n = 136) and HIV-negative controls (n = 47). To account forthe release of Trx into plasma due to hemolysis, the Trx measurementswere corrected according to the level of hemoglobin in the plasmasample. Data presented show that, in contrast to tissue Trxlevels, corrected plasma Trx levels are significantly higherin HIV-infected individuals than in controls (P < 0.0001).Furthermore, {small tilde}25% of the HIV-infected individualsstudied have plasma Trx levels greater than the highest levelfound in controls (37 ng/ml). Detailed multiparameter FACS analysisof peripheral blood mononuclear cells (PBMC) from the infectedindividuals demonstrates that those with higher plasma Trx levels(37 ng/ml or greater) tend to have lower overall CD4 counts.In addition, increases in plasma Trx levels correlate with decreasesin monochlorobimane staining (indicative of lower intracellularglutathione levels in PBMC) and with changes in surface antigenexpression (CD62L, CD38 and CD20) that occur in the later stagesof HIV infection. These correlations suggest that elevationof plasma Trx levels may be an important component of advancedHIV disease, perhaps related to the oxidative stress that oftenoccurs at this stage.     

Cross-linking of cell surface ganglioside GM1 induces the selective apoptosis of mature CD+ T lymphocytes

Gangliosides are glycosphingolipids found ubiquitously on thesurface of mammalian cells. They contain a ceramide tail thatis inserted into the membrane and exposed carbohydrate and sialicacid moleties. The non-toxic B subunit oligomer (EtxB) of Escherichiacoli heat-labile enterotoxin (Etx) is a potent immunogen invivo and has profound modulatory effects on EtxB-primed lymphocytesin vitro, properties which are dependent on its ability to bindto GM1 ganglioside receptors. Here, it is shown that cross-linkingGM1 by EtxB causes a differential effect on mature CD4⁺ andCD8⁺ T cells from lymph node cultures proliferating in responseto an unrelated antigen, ovalbumin. Addition of EtxB to suchcultures led to the complete depletion of CD8⁺ T cells comparedwith enhanced activation of CD4⁺ T cells [as measured by expressionof CD25 (IL-2R)]. By contrast, addition of a mutant EtxB, EtxB(G33D),which does not bind to GM1, failed to trigger CD8⁺ T cell depletion.When EtxB was added to isolated non-immune CD8⁺ lymphocytesrapid (12–18 h) alterations in nuclear morphology andthe appearance of sub-G₀/G₁ levels of DNA were induced; propertieswhich are characteristic of cells undergoing apoptosis. EtxB(G33D)failed to trigger apoptosis, indicating that the induction ofthe apoptotic signal was dependent on the binding of GM1. Thesefindings provide an insight into the potent immunogenicity andimmunomodulatory properties of E. coli enterotoxins as wellas heralding a novel method for the selective induction of apoptosisin mature CD8⁺ T lymphocytes.