Cellular basis for the age-associated increase in autoimmune reactions

Abstract

The mechanisms that lead to the increased expression of autoantibodies with age are poorly understood. We have studied the number, size, and density of spleen and peritoneal cells from young and old BALB/c and C57BL/6 mice as well as the frequency of clonal precursors for antibodies to mouse erythrocytes, thyroglobulin, and IgG In these lymphold preparations. Old mice have a 6-fold Increase in the number of resident peritoneal cells and a 2-fold increase In the absolute number of Ly1-bearing B cells in this population. Furthermore, old mice have twice as many large, low density splenic B cells as young mice. The frequencies of B cell clonal precursors for anti-BrMRBC and antl-thyroglobulln antibody-forming cells In old mice were 3–10 times greater than in young mice. In the same cultures, however, no increase In the frequencies of B cell clonal precursors for antl-IgG or anti-DNA antibody forming cells was detected In old compared to young mice. These findings and other data suggest that there are at least two families of B cell autoantlbody precursors, one Including antl-BrMRBC and anti-thyroglobulln autoantibodies, the other Including antl-IgG and anti-DNA antibodies. Studies of the differential regulation of these two families of autoantlbody precursors might contribute to a greater understanding of autoimmune phenomena in age and disease.