Phytohemagglutinin induced proliferation by aged lymphocytes: reduced expression of high affinity interleukin-2 receptors and interleukin-2 secretion |
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Authors: | C J Froelich J S Burkett S Guiffaut R Kingsland D Brauner |
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Institution: | Section of Rheumatology, University of Illinois College of Medicine, Chicago 60612. |
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Abstract: | Human lymphocytes from elderly and young donors were cultured with phytohemagglutinin. Cultures from two groups of aged donors, recruited respectively from our ambulatory clinic and a nursing home, incorporated less tritiated thymidine (3H-TdR) and secreted less interleukin-2 than did young donors. Furthermore, as determined for the first time by a radioligand binding receptor assay, the aged lymphoblasts possessed significantly fewer high affinity IL-2 receptors per cell. Despite a decrease in the number of high affinity receptor cells the dissociation constant (Kd) was comparable for the three groups. It was also shown that the amounts of soluble IL-2 receptors that were released into the supernatants by mitogen stimulated cells did not differ for the aged and young donors. These data suggest that defects in IL-2 production and high affinity IL-2 receptor generation may both be responsible for immune deficiency in the elderly. |
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