Abstract
The receptors for fibronectin (FN-R) and vitronectin (VN-R) belong to a family of integral membrane glycoproteins known to be involved in cell- extracellular matrix and cell-cell interactions named integrins (FN-R = beta 1 integrin and VN-R = beta 3 integrin). Adhesion studies using FN- coated plastic dishes and highly purified subpopulations of peripheral blood mononuclear cells (PBMCs) showed a strong binding of monocytes and T lymphocytes to FN but virtually no binding of B cells to FN. Binding of monocytes and T cells to FN could be partially inhibited by a hexapeptide (GRGDSP) containing the adhesive peptide sequence Arg-Gly- Asp (RGD) as well as by an anti-FN-R antibody. The distribution of beta 1 and beta 3 integrin complexes on PBMCs was characterized by immunoprecipitation of detergent extracts of 125I-labeled cells using polyclonal antibodies against these two receptors. Two surface polypeptides corresponding to the alpha and beta chains of FN-R and VN- R were found on all three cell types. To characterize these receptors further, monoclonal antibodies (MoAbs) against the very late antigens (VLAs) 1, 3, and 5 were used for immunoprecipitation studies. Monocytes and T cells reacted with VLA 5 that was previously identified as the human FN receptor, whereas no labeling with anti-VLA 5 could be shown for B cells. When cell populations were cultured in 10% human serum for 24 hours, an increase in beta 1-integrin+ monocytes and T cells was observed. The number of beta 3-integrin+ cells remained essentially unchanged. The presence of beta 1 and beta 3 integrins on monocytes as well as on T and B lymphocytes may be of significance in the ability of these cells to interact with each other and participate in hematopoiesis and certain immune reactions.
Isolating Human Peripheral Blood Mononuclear Cells and CD4+ T cells from Sézary Syndrome Patients for Transcriptomic Profiling
