The effect of human T and B lymphocytes on low-density lipoprotein catabolism by cultured fibroblasts.
Freshly isolated human peripheral blood B lymphocytes degrade LDL via the LDL receptor pathway to a considerably greater extent than do freshly isolated T lymphocytes. In this study, B and T lymphocytes were compared for their ability to modulate LDL degradation in fibroblasts to which they were exposed. B and T lymphocytes were purified by sheep red blood cells rosette formation and passage through a nylon column. Lymphocytes and skin fibroblasts were co-cultured for 48 h in 10% lipoprotein-deficient serum before 125I-labeled LDL was added for measurement of its degradation. Co-culture with B lymphocytes increased LDL degradation by fibroblasts in a dose-dependent manner, but co-culture with T lymphocytes, did not. B lymphocytes had the same effects on human smooth muscle cells. The enhancement of LDL degradation in fibroblasts also was observed when fibroblasts were exposed to conditioned medium from B lymphocytes. The effects of B lymphocytes were not reproduced by exposure of fibroblasts to purified immunoglobulins or to B lymphocytes that had been freeze-thawed. These findings suggest that a secretory product of B lymphocytes can increase LDL receptor activity in other cells.
D001402:B-Lymphocytes / Q000378:metabolism*; D002478:Cells, Cultured; D055598:Chemical Phenomena; D002621:Chemistry; D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D007136:Immunoglobulins / Q000494:pharmacology; D008077:Lipoproteins, LDL / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000302:isolation & purification*; D011973:Receptors, LDL; D013601:T-Lymphocytes / Q000378:metabolism*
D007136:Immunoglobulins; D008077:Lipoproteins, LDL; D011956:Receptors, Cell Surface; D011973:Receptors, LDL