[Age-associated changes in antibody production of murine spleen cells]

In the present work, we studied age-associated changes in murine immune functions. We estimated total antibodies and autoantibodies to single-stranded DNA (ss-DNA), double-stranded DNA (ds-DNA) histone and collagen in sera and culture supernatants of spleen cells from young and aged BALB/c, C57BL/6 and MRL/MpJ-(+/+) (MRL/n) mice. In MRL/n mice, the IgM class of the total antibody level in serum increased gradually to the maximum at 3 months of age, and then started to decrease. In contrast, the IgG class started to rise with age after the age of 9 months. Serum levels of IgM and IgG autoantibodies to DNA were dominant in MRL/n mice, and the IgG class started to increase in earlier stages of life than in BALB/c and C57BL/6 mice. Anti-DNA autoantibodies were produced in lipopolysaccharide (LPS)-stimulated cultures of spleen cells from BALB/c, C57BL/6 and MRL/n mice. The stimulatory effect of LPS on autoantibody production was significantly reduced by the addition of concanavalin A (Con A) to the LPS-stimulated cultures. The Con A-induced suppressive activity increased with the donor age in MRL/n mouse spleen cells. On the other hand, total antibody production in LPS-stimulated cultures was not affected by the addition of Con A to the cultures. These results may suggest that IgG autoantibody-producing B cells increase with age in MRL/n mouse spleen cells, and that the suppressive activity on autoantibody production is selectively augmented.