The impact of aging on mucosal immune responses, particularly IgA production, is controversial. Many previous studies haven’t separated effects of the aged microenvironment (i.e. aged T cells, homing molecule expression, antigen exposure) from intrinsic B cell defects. We hypothesized that life-history of cognate antigen exposure influences function and distribution of mucosal B cell populations during aging. These studies used immunoglobulin transgenic mice, whose cognate antigen nitrophenyl is not naturally encountered. Mice were periodically immunized orally from birth with T cell-dependent or -independent antigens. At various ages, intestines were analyzed for relative abundance, size, and cellular composition of Peyer’s Patches and isolated lymphoid follicles. Results revealed significantly more isolated lymphoid follicles in the distal region of aged mice when compared to young. Comparing immunized and control mice, flow cytometry data reveals a significant decrease in percentages of transgenic B cells in both tissues, and in animals receiving T cell independent antigen there were changes in CD4 and CD8 T cell distribution in aged mice. There was also a significant decrease of transgenic B cells in aged mice immunized with a T cell-dependent antigen for both Peyer’s Patches and isolated lymphoid follicles. Hence, preliminary data suggests significant role of cognate antigen exposure and further elucidates the mechanisms of age-related immune dysfunction.
- Copyright © 2013 by The American Association of Immunologists, Inc.