Basis for the age-related decline in intestinal mucosal immunity.

The elderly are characterized by mucosal immunosenescence and high rates of morbidity and mortality associated with infectious diseases of the intestinal tract. Little is known about how the differentiation of immunoglobulin A (IgA) plasma cells in Peyer's patches (PPs) and their subsequent homing to the small intestinal lamina propria (LP) is affected by aging. Quantitative immunohistochemical analyses demonstrated a 2-fold increase in the number of IgA+ cells in the PPs, coupled with significant declines in the numbers of IgA+ and antibody-positive cells in the intestinal LP of senescent rats compared to young adult animals.