Evidence for regulation of human colonic mucosal immunoglobulin secretion by intestinal lymphoid cells

In vitro immunoglobulin secretion has been studied using isolated colonic mucosal lymphoid cell populations obtained from 41 patients with non-inflammatory intestinal disease. Cell fractions were separated into intra-epithelial and lamina propria-enriched populations. The secretion of immunoglobulins by mucosal cells appeared to be independent of mitogen stimulation. When intra-epithelial lymphocyte preparations were co-cultured with autologous lamina propria lymphocytes, the secretion of IgM was significantly depressed but that of IgA and IgG was preserved. Co-cultured of mucosal cells with autologous peripheral blood lymphocytes resulted in suppression of pokeweed mitogen stimulated and unstimulated immunoglobulin secretion. Lamina propria T cells were shown to provide helper function for the in vitro secretion of IgA and IgM but not IgG, by autologous peripheral blood B cells. Immunoglobulin secretion by lamina propria lymphocytes was shown to be partly dependent on the concentration of E-rosette forming cells. These experiments demonstrate that human colonic mucosal lymphoid cells contain specific populations of helper and suppressor cells which selectively control intestinal immunoglobulin secretion.