SURFACE-ANTIGEN EXPRESSION IN SPLEEN-CELLS OF C57B1 6 MICE DURING AGING - INFLUENCE OF SEX AND PARITY/

So far all studies on the murine ageing process have been conducted on virgin mice. Immune ageing may be influenced by sex hormone differenc es related to sex or pregnancies. The aim of this study was to investi gate whether pregnancies and gender influence the cell changes observe d during ageing in a peripheral lymphoid compartment of C57B1/6 mice. Using how cytometry, changes in (Thy1.2(+)) T cell, (B220(+)) B cell a nd (CD11b/Mac-1) macrophage spleen populations were monitored in 2, 8 (3 months after last pregnancy) 15 and 23-month-old mice including mal es, virgin and multiparous females. The development of naive (CD44(low )), memory (CD44(high)), activated/memory (MEL-14, CD62L) cells were i nvestigated in CD4(+) and CD8(+) T cell subsets. Both shea term (at 8 months) and long term (at 15 and 23 months) effects of multiparity wer e obvious in the lymphocyte/macrophage population changes associated w ith the ageing process. Short-term effects included delayed appearance of CD4(+)CD44(high) memory lymphocytes and increased numbers of both CD4(+)MEL-14(low) activated/memory cells and Mac-1(+) macrophages when compared with virgin control mice. Later effects of multiparity were increased CD8 alpha(dull) populations and increased T/B cell ratios an d the ratio of memory to naive CD4(+) cells (CD44(+high)/CD44(+low)). A sex effect was noticed: males exhibited lower Mac-1(+) levels and me mory/naive ratio in CD4(+) subset than virgin females throughout life. These results suggest that gender and/or pregnancies affect the age-r elated distribution of lymphoid and macrophage cell populations in the spleen of C57B1/6 mice.