Adhesion of thymocytes to bone marrow stromal cells: regulation by bFGF and IFN-gamma.
We recently reported on selective interactions between immature T cell subpopulations and bone marrow (BM) stromal cells. To further study this process, we first examined the efficacy of methods estimating cell-cell adhesion and then investigating the effects of cytokines on thymocyte-stroma associations. Techniques based on the use of the fluorochromes calcein-acetomethylester (calcein-AM) and fluorescein diacetate (FDA) were studied and compared to regular cell counting methods. With calcein-AM labeling, the retention time was relatively long, while with FDA labeling, there was a rapid cellular efflux. Using calcein-AM, we developed an accurate quantitative fluorometric assay for determining the adherence of thymocytes to a BM stromal cell line (MBA-13). A maximal fraction of about 29% thymocytes was found to adhere to confluent MBA-13 cell layers after four to six h of coculture. Whereas interleukin 1 did not change the rate of adhesion of thymocytes to the stroma, interferon-gamma (IFN-gamma) significantly increased adhesion. Basic fibroblast growth factor (bFGF) had a dose-dependent biphasic effect on thymocyte adhesion, and a greater fraction of double negative thymocytes adhered to stroma pretreated with bFGF. Taken together, these results suggest that IFN-gamma and bFGF modulate T cells-BM stromal cell adhesion.
Barda-Saad
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Department of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel.
Zhang
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Zipori
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Rozenszajn
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D000818:Animals; D001854:Bone Marrow Cells; D002448:Cell Adhesion / Q000187:drug effects; D002460:Cell Line; D005069:Evaluation Studies as Topic; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D005434:Flow Cytometry; D005452:Fluoresceins; D005456:Fluorescent Dyes; D007371:Interferon-gamma / Q000494:pharmacology*; D007375:Interleukin-1 / Q000494:pharmacology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008855:Microscopy, Electron, Scanning; D017154:Stromal Cells / Q000166:cytology* / Q000187:drug effects / Q000648:ultrastructure; D013601:T-Lymphocytes / Q000166:cytology* / Q000187:drug effects / Q000648:ultrastructure
D005452:Fluoresceins; D005456:Fluorescent Dyes; D007375:Interleukin-1; D016222:Fibroblast Growth Factor 2; D007371:Interferon-gamma; C007740:fluorexon