Differences in the immunoglobulin synthesis by peripheral blood lymphocytes in Crohn's disease and ulcerative colitis.

To determine whether patients with Crohn's disease and ulcerative colitis differ in their capacity to produce immunoglobulins, we have studied the in vitro immunoglobulin synthesis by peripheral blood lymphocytes of such patients and compared the results with those of healthy controls. The spontaneous immunoglobulin production by peripheral blood lymphocytes from Crohn's disease patients was significantly increased for both IgA and IgG, whereas for IgM the increase did not reach statistical significance. In ulcerative colitis, however, the spontaneous IgA and IgG production was almost identical to that of the healthy controls and thus lower than in Crohn's disease. Pokeweed mitogen stimulation resulted in a significantly enhanced immunoglobulin production in Crohn's disease and in controls, whereas peripheral blood lymphocytes from ulcerative colitis patients were found to be rather insensitive to pokeweed mitogen stimulation. Suppression of the stimulated immunoglobulin production by concanavalin A revealed considerable reduction in all groups studied. In general, the highest suppression was found in patients with Crohn's disease. In patients with Crohn's disease or ulcerative colitis there was no relation between the changes in the in vitro immunoglobulin synthesis and the population of B or T lymphocytes and monocytes present in the peripheral blood. The differences in the spontaneous and stimulated immunoglobulin synthesis by peripheral blood lymphocytes, as found in this study, point to major changes in the regulation of the immunoglobulin synthesis in Crohn's disease and ulcerative colitis.