Changes in the amount and level of phosphorylation of p56(lck) in PBL from aging humans.

The effects of aging on the activation of the cytoplasmic tyrosine protein kinase p56(lck) have been investigated in PBL from adult and elderly subjects upon activation with mitogens or different co-stimuli. Results show that the amount and phosphorylation of p56(lck) are reduced in PBL from elderly as compared to adult subjects. This finding suggests that alterations in p56(lck) may contribute to the age-associated loss of some T cell functions, such as proliferation and IL-2 production, which are found decreased in PBL from old individuals. However, p56(lck) seems irrelevant to the production of IFN-gamma and IL-4 which were both found increased in the PBL from old subjects, as expected from the relative expansion of memory versus naive T cell subpopulations in aging.