Immunoregulatory defects in murine aged Peyer's patches

Aging effect on immunoregulatory processes in Peyer's patches (PP) from BALB/c mice of 3-4 months and 24-28 months was studied in vitro. The magnitude of isotype-specific Ig production by aged or young PP B cells in co-culture with young or old fresh PP T cells strongly suggested that the suppressor activity of PP T cells was impaired in aged mice. Further studies on in vitro induction of concanavalin A-activated T helper cells, T suppressor-inducer cells and T suppressor cells from aged PP indicated that the generation of T suppressor cells was largely impaired, in contrast to a minor defect(s) in that of T helper cells. The findings obtained here at least suggest that in aged PP, a T suppressor-inducer cell subset appears to be more selectively impaired in the aging process than the other lymphocyte subpopulations, which possess minor intrinsic functional defects. Thus, these abnormal T and B cell responses in PP could be responsible for the senescence-associated gut mucosal immunologic dysfunction.