Immunosenescence of the human B cell system: impaired activation/proliferation in response to autologous monocytes pulsed with Staph protein A and the effects of interleukins 1 and 2 compared to interferon.

Experiments were performed to compare the activation/proliferation characteristics of B cells from elderly and young humans which were triggered by autologous monocytes pulsed with Staph protein A and to also evaluate the influence of biologically active molecules on B cell responsiveness. B cells from most elderly subjects had lower proliferative responses than did B cells from young subjects. Both interleukin 1 (IL 1) and IL 2 were capable of increasing the diminished B cell responses of certain elderly subjects while the responsiveness of other elderly subjects required either higher concentrations of IL 2 than young subjects or remained unchanged. Although interferon typically failed to influence the responses of young or aged adults, the responses of some aged adults were unexpectedly increased or decreased. Flow microcytofluorometry (FMF) analysis revealed that B cells from certain elderly subjects demonstrated distinct differences in surface IgM/D expression or light scattering characteristics as compared to B cells from young subjects. However, the FMF characteristics of B cells from elderly subjects were not closely linked to the activation/proliferation capabilities. These data suggest that B cells from certain elderly subjects are responsive to biologically active molecules but that immunosenesence of the B cell system perturbs the normal relationship between the phenotypic and functional characteristics of B cells.