Aging and the mobilization of intracellular calcium by phytohemagglutinin in human T cells.
Studies of T cell surface marker expression have shown that the diminished response of peripheral blood T cells from healthy older subjects to mitogens is not due to decreased expression of the CD3/Ti antigen receptor complex or imbalance in regulatory subsets. To determine if there is a defect in transmembrane signaling we have followed kinetics of increase in intracellular free calcium with Indo-1 after addition of phytohemagglutinin (PHA) to cells from healthy old and young adults. Using both flow cytometry and spectrofluorimetry, we find no differences in increase in mean calcium concentration and only a small decrease in number of cells with increased free calcium very early (1 minute after PHA) in the response of the older subjects' cells. It appears that the major age-associated defect(s) in signal transduction in human T cells may involve either early biochemical steps parallel to calcium mobilization or steps subsequent to transmembrane signaling.
Lustyik
G
G
Department of Laboratory Medicine and Pathology, University of Minnesota.
O'Leary
J J
JJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000276:immunology*; D002118:Calcium / Q000097:blood*; D002469:Cell Separation; D005260:Female; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D066298:In Vitro Techniques; D008213:Lymphocyte Activation; D008297:Male; D010835:Phytohemagglutinins / Q000494:pharmacology*; D015398:Signal Transduction; D013050:Spectrometry, Fluorescence / Q000379:methods; D013601:T-Lymphocytes / Q000378:metabolism*
D010835:Phytohemagglutinins; D002118:Calcium