Aging and immune system - Influence of sex and parity

So far no comparative studies have been conducted to know whether physiolog ical influences related to sex hormonal differences affect the age-related changes of the immune system. The aim of this study was to investigate whet her pregnancies and sex influence the age-related changes in the peripheral lymphoid compartment and functions of T cells in mice. Using flow cytometr y, we examined changes in (Thy1.2+) T cells, (B220+) B cells and (CD11b/Mac -1+) macrophages in the spleen of multiparous and virgin females and males at 2, 8 15 and 23 months of age. The development of naive (CD44low) and mem ory (CD44high) cells were investigated in CD4+ and CD8+ T cell subsets. To analyze the age-related changes in functions of T cells, we examined the se cretion of some T cell immunoregulatory cytokines (IL-2, IL-4, gamma-interf eron and GM-CSF) of in vitro Concanavalin A-activated spleen cells of C57BL /6 mice. Both short term (8 months) and long term (15-23 months) effects of pregnancies were obvious in the age-related changes of the immune system S hort term effect included delayed appearance of memory CD4+ cells and the p reserved IL - 2 production. At eight months, shortly after pregnancies, bot h parameters were higher in multiparous females. Later effects of pregnanci es were evidenced by a higher level of macrophages (Mac-1+) than in other g roups throughout lift. The increased gamma-interferon, IL-4 and GM-CSF prod uctions appeared earlier at 15 months, IL-4 and GM-CSF levels remained high er in multiparous females than in virgin females and males in late adulthoo d Sex differences were also noticed: males exhibited lower macrophage level s after one year and gamma-interferon secretion capacity than females in la te lift. This study underlines that the onset, magnitude and kinetics of th e age-related changes in the distribution of immune cells and T cell functi ons are parity - and sex-dependent. These changes may influence the inciden ce of age-related diseases and may explain the greater longevity of women, especially the multiparous ones.