Interleukin-10 enhances immune responses to pneumococcal polysaccharides and sheep erythrocytes in young and aged mice

Antibody responses to pneumococcal polysaccharides are decreased in aged mi ce. Using a system to measure murine antibody responses to the Pnu-Imune va ccine, here we demonstrate that interleukin-10 (IL-10) has an adjuvant effe ct in enhancing the vaccine response in the aged. IL-10 increased the vacci ne responses of B cells from aged mice in vitro only if either T cells or m acrophages were also present. The need for T cells or macrophages could be substituted by cytokines such as IL-1 or IL-5, which are normally made by t hese accessory cells. Thus, IL-10 appeared to act on B cells directly but i t worked in conjunction with other cytokines to induce an antigen specific response. In vivo studies showed that IL-10 administration enhanced antibod y responses not only to thymic independent antigens but also to thymic-depe ndent antigens such as sheep erythrocytes. These data suggest that IL-10 ma y be useful in enhancing vaccine-specific responses in situations in which the host is immunocompromised. (C) 1999 Academic Press.