Age- and training-related events in active T subpopulation - Changes in polyphosphoinositide metabolism during mitogenic stimulation

To examine the effects of age and training an the active T subpopulation we considered elderly amateur cyclists over 65 in comparison with young amateur cyclists and young and aged sedentary healthy controls. Significant differences were observed between trained and sedentary elderly subjects consisting of an increase in the percentage of active E rosettes after 4 and 24 h of in vitro PHA stimulation, and of a decrease in the in vitro phosphorylation of phosphatydylinositol 4,5-bisphosphate (PtdInsP(2)) and a corresponding increase in phosphatydylinositol 4-phosphate (PtdInsP) in the early steps of the mitotic response. Our findings support the hypothesis of the involvement of inositol lipids in controlling the expression of lymphocyte surface receptors.