Deficiency of intestinal immunity with graft-vs.-host disease in humans.

A possible deficiency of secretory immunity was investigated in 55 bone marrow recipients and nine control patients by evaluation of lamina propria plasma cells, Peyer's patch and mesenteric lymph node cellularity, and mucosal injury. All short-term survivors had marked depletion of Peyer's patch and mesenteric lymph node cellularity; long-term survivors demonstrated repopulation. In autologous or syngeneic marrow recipients and patients without engraftment, the intestines contained numerous IgA-bearing, IgM-bearing, and total plasma cells, compared with a marked decrease in these cells in patients with allogeneic engraftment. Patients with graft-vs.-host disease (GVHD) had even fewer IgA-bearing plasma cells and much greater mucosal injury. These results suggest that with allogeneic engraftment and GVHD, host intestinal plasma cells are depleted before repopulation and maturation of Peyer's patches and mesenteric lymph nodes with donor cells. These patients, therefore, are at increased risk for infection by intestinal organisms.