Age-related alterations in actin cytoskeleton and receptor expression in human leukocytes.
We studied a number of parameters, which may all depend upon cytoskeletal function, comparing lymphocytes and granulocytes (PMN) from young and old healthy donors. F-actin content was measured by NBD-phallacidin staining, followed by flow cytometry and was expressed as mean channel fluorescence (MCF). There were no differences in the basal F-actin content of PMN obtained from young (under 35 years old) and old donors (above 65 years). In contrast, the basal F-actin content was higher in lymphocytes obtained from the old donors (MCF, 56.8 +/- 2.9 vs 48.1 +/- 2.6 in the young; mean +/- SEM, n = 20, p less than .03). Stimulus-induced actin polymerization was slightly lower in the older age-group both in PMN and lymphocytes, but a significant difference was found only in PMN stimulated with the chemotactic peptide, N-formyl-methionyl-leucyl-phenylalanine (MCF 97.9 +/- 4.7 vs 88.6 +/- 3.4; young vs old, mean +/- SEM, n = 20, p less than .05). Interleukin-2 receptor expression was measured by staining with FITC-conjugated anti-CD25 antibodies and flow cytometry, following stimulation with phytohemagglutinin (PHA) or pokeweed mitogen (PWM). Perturbation of the cytoskeletal system with pentoxifylline, which has been shown to decrease F-actin content and inhibit the expression of several cell surface receptors, had similar effects on leukocytes from young and old donors.(ABSTRACT TRUNCATED AT 250 WORDS)
Rao
K M
KM
Geriatric Research, Education and Clinical Center, VA Medical Center, Durham.
Currie
M S
MS
Padmanabhan
J
J
Cohen
H J
HJ
D000199:Actins / Q000032:analysis*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism*; D002453:Cell Cycle; D002478:Cells, Cultured; D005434:Flow Cytometry; D006098:Granulocytes / Q000276:immunology; D006801:Humans; D007962:Leukocytes / Q000166:cytology / Q000378:metabolism*; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000378:metabolism; D016177:Macrophage-1 Antigen / Q000032:analysis; D008875:Middle Aged; D009961:Orosomucoid / Q000032:analysis; D010456:Peptides, Cyclic; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic / Q000032:analysis*; D015375:Receptors, Interleukin-2 / Q000032:analysis*
D000199:Actins; D016177:Macrophage-1 Antigen; D009961:Orosomucoid; D010456:Peptides, Cyclic; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2; C017613:phallacidin