Effect of age on the gastrointestinal-associated mucosal immune response of humans

Age-related changes in gastrointestinal-associated mucosal immune response have not been well studied. Thus, we investigated the effect of age on this response and compared these responses to those of peripheral immune cells. Saliva, blood, and intestinal biopsies were collected from young and old h ealthy subjects to determine immunoglobulin (Ig) levels and to isolate peri pheral blood mononuclear cells, intraepithelial lymphocytes (IELs), and lam ina propria lymphocytes (LPLs). Although subject age did not influence the level of total IgA found in saliva, IgA levels in serum increased (p < .05) with age. Older subjects' peripheral blood mononuclear cell proliferation and IL-2 production were significantly lower than those of young subjects. LPLs from older subjects produced significantly less IL-2 in response to al l stimuli than did that from the young. IEL's ability to proliferate and pr oduce IL-2 was not affected by subject age. Thus, LPL but not IEL demonstra ted an age-related decline in immune function similar to that seen in perip heral lymphocytes.