Search

Kupffer cells, ED2+ macrophages of the liver, play an important role in liver damage and regeneration. It is proposed that Kupffer cells are stationary and regenerate after acute liver trauma by local proliferation. We analyzed their kinetics in three surgically relevant murine models of acute liver injury: partial liver resection, ischemia with reperfusion and sepsis. We found an early increase in ED2+ cells after 0.5 h and a maximum after 12 h. These results suggest an infiltration of the cells early after the injury and a later local proliferation. These ED2+ macrophages are localized predominantly periportally; nearly no macrophages are found pericentrally, except in the sepsis model. Therefore, a shifting of macrophages from portal to central seems to be unlikely, suggesting a hepatic zonation of homing factors. Copyright © 2005 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

SUMMARY CVID is characterized by reduced serum levels of all switched immunoglobulin isotypes (IgG, IgA, IgE) predisposing patients to recurrent infections of their respiratory and gastrointestinal tract. Correspondingly, most CVID patients exhibit a severely decreased proportion of class switched memory B cells (CD19+ CD27+ IgD- IgM- IgG+ or IgA+ ) in their peripheral blood (CVID type I). We previously identified a subgroup of CVID patients showing a significantly reduced expression of CD86 and CD137 following activation in vitro of PBMC or purified B cells (CD19+ ) with anti-IgM plus IL-2. Here we extend our previous studies by asking whether highly purified, cell-sorted naive B cells show already an expression defect of B cell surface molecules relevant in activation (CD39, CD69), differentiation (CD24, CD27, CD38) or T–B interaction (CD25, CD70, CD86). We stimulated cell-sorted, naive B cells (CD19+ CD27- IgM+ IgDhigh IgG- IgA- ) from 10 CVID patients and 10 healthy controls for 4 days with anti-IgM plus IL-2 in the absence or presence of autologous CD4+ T cells and measured the expression of the referred surface molecules. Based on reduced or normal numbers of switched memory B cells the CVID patients had previously been classified into eight type I patients and two type II patients, respectively. Interestingly, only the molecules CD25, CD70 and CD86, all relevant in cognate T–B interaction, showed a significantly lower expression in naive B cells from CVID patients compared to controls. While coculture with autologous CD4+ T cells normalized the CD25 expression, CD70 and CD86 expression remained subnormal, notably in the eight CVID patients of type I. These findings strongly suggest an intrinsic signalling or expression defect for CD70/CD86 at the level of naive B cells in type I... [ABSTRACT FROM AUTHOR]

The expression of Fas ligand (FasL) by malignant cells might be a mechanism for tumor immune escape. We investigated FasL expression by LS 174T colon carcinoma cells. Furthermore, the effects of in vitro stimulation with rIL-2, rIFN-γ and rTNF-α were investigated with regard to a possible regulation of the FasL expression by cytokines. FasL expression was detected by flow cytometry and RT-PCR. We observed a spontaneous expression of FasL by LS 174T cells. Incubation with high-dose rTNF-α induced an upregulation of FasL of 23%. rIL-2 and rIFN-γ did not significantly affect FasL expression. To control whether our cytokine stimulation experiments were suitable to prove an upregulation of membrane proteins by tumor cells, we investigated the expression of ICAM-1, N-CAM, CD44s, CD44v6 and CD44v10. These adhesion molecules were spontaneously expressed by LS 174T cells. Only ICAM-1 and CD44v10 were significantly upregulated by rIFN-γ and rTNF-α, respectively. These results could indicate that cytokines, released by tumor-infiltrating leukocytes, may induce the FasL-dependent apoptotic signal by which tumors downregulate an immunological host response. Copyright © 1999 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Several lines of evidence argue in favour of an involvement of T cells in the pathogenesis of Wegener's granulomatosis (WG). These include the presence of highly specific IgG autoantibodies to proteinase 3, perivascular T-cell infiltrates and elevated amounts of soluble interleukin-2 (IL-2) receptors in patient's serum. In order to further address this question we evaluated by double immunoflourescence and flow cytometry the expression of several cell surface molecules associated with T-cell activation. As compared to healthy controls ( n=15), the CD4 subset was significantly diminished, while the percentage of CD8 T cells was elevated in WG patients ( n=24). Within the CD4 T-cell subset we found a highly significant increase in activation/memory markers (CD25, CD29, HLA-DR). Within the CD8 T-cell subset the expression of CD11b, CD29 and CD57 was significantly elevated, while the expression of VD28 was reduced. The use of 10 Vβ-, 1 Vα-and 1 Vγ-specific monoclonal reagents failed to reveal any significant bias in the peripheral T-cell receptor V-gene repertoire of WG patients. There was also no correlation between T-cell activation markers and laboratory parameters [C-reactive protein (CRP), ESR], disease duration or therapy. A significant correlation was found only for the degree of organ involvement and the increase in CD4 T cells coexpressing HLA-DR, as well as the increase in CD57 expression on CD8 T cells. In conclusion, both CD4 and CD8 T-cell subsets were activated in WG. Cytotoxic CD8 CD57 CD11b CD28 T cells may directly contribute to damage of vascular endothelium. [ABSTRACT FROM AUTHOR]

We investigated the expression of surface molecules on lymphocytes from 20 patients with CVID and 40 healthy subjects. Lymphocytes were analysed by dual colour flow cytometry. We identified a subset of patients (8 of 20) characterized by low CD4/CD8 ratio (< 1.1), expansion of T cells co-expressing the activation marker HLA-DR and significant increase in CD8+ T cells co-expressing CD57. Expression of the adhesion molecules LFA-3 (CD58) and ICAM-1 (CD54) was significantly increased in this subgroup. In addition, within theCD4+ T cells the percentage of CD29+ (memory) cells was increased, while the CD45RA and LAM-1 (Leu-8) antigens were depressed. These results indicate that in a subgroup of CVID patients T cells are activated in vivo and the CD57+CD8+ lymphocyte subpopulation, supposed to comprise functional suppressor T cells, is expanded. We suggest a chronic viral infection in these patients, but it is not clear whether this is primary or secondary to the underlying defect. [ABSTRACT FROM AUTHOR]

In sera of patients with mixed connective tissue disease (MCTD, Sharp Syndrome) high titres of IgG autoantibodies to U1snRNP-specific proteins are found. The isolated occurrence of these autoantibodies is highly associated with the HLA-DR4 haplotype. snRNP-specific T cells are supposed to be involved in this autoantibody production. To address this question we cultured mononuclear cells from MCTD patients and healthy donors with a highly purified UsnRNP preparation from HeLa cells using bulk or limiting dilution cultures. Secondary responses to snRNP were detected only rarely with T cell lines from two patients and two controls, and turned out to be unstable during further expansion. One T cell line derived from a healthy individual retained its snRNP reactivity upon limiting dilution cloning and could be characterized in detail. The CD4+ T cell clone recognized native snRNP particles presented by monocytes in an HLA-DR4 (BI *0401) restricted manner. Separation of the protein and RNA moieties of snRNP particles revealed that the T cell clone responded specifically to the protein fraction, but not to RNA and diverse control antigens. Sequencing of the T cell receptor α and β chain cDNAs revealed that the clone used the Vα 14.2 and Vβ14 elements. Upon antigen-specific and mitogenic stimulation the T cell clone showed a Th1-specific cytokine pattern, and did not provide helper activity for in vitro immunoglobulin production. This study demonstrates the presence of self-reactive snRNP-specific T cells in a healthy donor. The T cell clone may not represent a helper T cell for the formation of U1 snRNP-specific autoantibodies. [ABSTRACT FROM AUTHOR]