Age-associated changes in proliferative and differentiative response of human B cells and production of T cell-derived factors regulating B cell functions.
The abilities of highly purified B cells to repeat replication for clonal expansion and to differentiate into immunoglobulin secreting cells (ISC) were examined in the aged and young groups. B cells from the aged showed twofold less proliferative response to B cell mitogen Cowan 1 (SAC) than those from the young. The original clone size of SAC responding B cells determined by colchicine block and [3H] thymidine [( 3H] TdR) uptake was not significantly reduced in the aged whereas the ability to repeat replication to expand clonal size was significantly reduced. B cells from aged and young persons were induced into ISC by combined stimulation with SAC and partially purified B cell differentiation factor (BCDF) free of IL-2 activity. ISCs for IgG and IgA were rather increased or at least not reduced in number in the aged as compared with those in the young. We also determined the IL-2 and BCDF activity produced by T cells from aged and young persons. Upon PHA stimulation, the aged T cells produced tenfold less IL-2 activity and threefold higher BCDF activity than did young T cells. Approximately threefold increase in spontaneous secretion of BCDF activity by aged T cells was found as compared with young T cells. The inverse correlation between the IL-2 activity and BCDF activity was found when both activities were determined in the same samples.
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000276:immunology* / Q000378:metabolism; D001402:B-Lymphocytes / Q000276:immunology*; D002454:Cell Differentiation; D002478:Cells, Cultured; D005260:Female; D006133:Growth Substances / Q000096:biosynthesis*; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism; D007376:Interleukin-2 / Q000096:biosynthesis*; D015847:Interleukin-4; D008213:Lymphocyte Activation; D008222:Lymphokines / Q000096:biosynthesis*; D008297:Male; D008934:Mitogens / Q000494:pharmacology; D013601:T-Lymphocytes / Q000378:metabolism*
D006133:Growth Substances; D007074:Immunoglobulin G; D007376:Interleukin-2; D008222:Lymphokines; D008934:Mitogens; D015847:Interleukin-4