Changes in peripheral immune cell numbers and functions in octogenarian walkers - an acute exercise study.

BACKGROUND: Age-related changes of the immune system, termed immunosenescence, may underlie the increased risk of infections and morbidity in the elderly. Little is known about the effects of acute exercise on peripheral immune parameters in octogenarians. Therefore, we investigated acute exercise-induced changes in phenotype and function of the immune system in octogenarians participating in the 2013 edition of the Nijmegen Four Days Marches. Blood sampling was performed at baseline and immediately after 4 days of the walking exercise (30 km/day). A comprehensive set of adaptive and innate immune traits were enumerated and analyzed by flow-cytometry. Peripheral blood mononuclear cells, isolated before and after walking were stimulated with LPS and supernatants were analysed for IL-1β, IL-6, IL-8 and TNF-α concentrations by ELISA. CMV serostatus was determined by ELISA. RESULTS: The walking exercise induced a clear leucocytosis with numerical increases of granulocytes, monocytes and lymphocytes. These exercise-induced changes were most profound in CMV seropositive subjects. Within lymphocytes, numerical increases of particularly CD4+ T cells were noted. Further T cell differentiation analysis revealed profound increases of naïve CD4+ T cells, including naïve Treg. Significant increases were also noted for CD4+ memory T cell subsets. In contrast, only slight increases in naïve and memory CD8+ T cell subsets were detected. Exercise did not affect markers of immune exhaustion in memory T cell subsets. NK cells demonstrated a numerical decline and a change in cellular composition with a selective decrease of the mature CD56(dim) NK cells. The latter was seen in CMV seronegative subjects only. Also, a higher IL-6 and IL-8 production capacity of LPS-stimulated PBMC was seen after walking. CONCLUSION: In this exceptional cohort of octogenarian walkers, acute exercise induced changes in immune cell numbers and functions. A clear response of CD4+ T cells, rather than CD8+ T cells or NK cells was noted. Remarkably, the response to exercise within the CD4+ T cell compartment was dominated by naïve CD4+ subsets

Generation and functional characterization of anti-clonotype antibodies to human T-cell receptors

Monoclonal antibodies (mAb) directed against the clonotypic structure of the T-cell receptor (TCR) may be useful reagents in the study and therapy of T-cell-mediated diseases. In contrast to several reports concerning the generation of anti-clonotype mAb to mouse TCR, only very limited numbers of anti-clonotype mAb to human TCR have been described. So far, a suitable method for the generation of anti-clonotype mAb to a given TCR has not been available and in this report we describe a novel strategy for the generation of such mAb. Mice were immunized with intact human T-cells. Then, spleen cell populations were precleared from B-cells reactive to CD3 and the constant region of the TCR by adsorption to TCR/CD3 complexes derived from an irrelevant T-cell clone. Subsequently, clonotype-specific B-cells were selected with TCR/CD3 complexes from the T-cell clone of interest. The small number of B-cells resulting from this selection were clonally expanded in a B-cell culture system and then immortalized by mini-electrofusion. Ten clonotype-specific mAb were generated against a DRBI *0401-restricted T-cell clone recognizing an epitope of the human cartilage glycoprotein 39 (HC gp-39) All mAb immunoprecipitated a heterodimeric 85 kDa protein. Absolute specificity was demonstrated in a T-cell agglutination test with the T-cell clone of interest compared to a set of 16 defined, irrelevant T-cell clones or lines. In functional assays, the mAb were found to inhibit or block antigen-specific T-cell stimulation. In addition, crosslinked mAb were found to stimulate proliferation of the specific clone in the absence of antigen and antigen presenting cells (APC). Such mAb may have clinical relevance in deleting or modulating autoreactive T-cells in a clonotype-specific manner. (C) 1997 Elsevier Science B.V

ANTIGEN-PRESENTING CAPACITY OF RHEUMATOID SYNOVIAL FIBROBLASTS

In normal, healthy joints, synovial fibroblasts do not express major histocompatibility complex (MHC) class II molecules. However, in inflamed joints of rheumatoid arthritis (RA) patients, synovial fibroblasts show an abundant expression of MHC class II. Does this increase in expression have functional consequences for antigen presentation to T cells? To date, the precise role of synovial fibroblasts in antigen presentation has not been documented. Here, we show by three different examples that cultured synovial fibroblasts with interferon-gamma (IFN-gamma)-induced MHC class II expression are capable of processing soluble protein for presentation to CD4(+) T cells. First, the antigen-presenting cell (APC) function of synovial fibroblasts was studied in an autologous model. From synovial tissue of a RA patient both a fibroblast cell line and a tetanus toroid (TT)-specific CD4(+) T-cell line were generated. A dose-dependent TT response was observed only when TT was presented by IFN-gamma-pretreated synovial fibroblasts. As more direct evidence for MHC class II-restricted antigen presentation, the response of a Mycobacterium tuberculosis-specific CD4(+) T-cell clone isolated from rheumatoid synovial fluid was demonstrated in the presence of synovial fibroblasts. The response was DR4Dw4-restricted and could be inhibited by monoclonal antibody (mAb) to HLA-DR. In addition, the lymphokine secretion pattern of the synovial T-cell clone did not differ qualitatively upon antigen-specific stimulation using pheripheral blood mononuclear cells (PBMC) or synovial fibroblasts as APC. In order to provide evidence for intracellular antigen processing we next examined the response of a M. leprae-specific T-cell clone with known epitope specificity. Our data suggest that synovial fibroblasts are not passive bystanders, but can become active participants in the development and maintenance of chronic inflammation