In vitro immune cell function in six cases of immunoproliferative small intestinal disease after long term remission.

We have studied several parameters of in vitro immune cell function in peripheral blood mononuclear cells from six patients with immunoproliferative small intestinal disease after long term remission. We have observed two groups of patients with different patterns of response. (a) After stimulation with pokeweed mitogen (PWM) and Staphylococcus aureus, three patients showed a significant reduction of the Ig synthesis (A, G and M) and the proliferative response. In two of them, we found increased spontaneous suppressor T cell activity. In the third case, the diminished response could not be attributed, according to our assays, either to suppressor T cells, lack of T helper activity (although the number of OKT4+ cells was diminished) or an intrinsic B cell defect. The three patients showed normal or augmented NK activity and an inversion of the OKT4+/OKT8+ ratio was detected in two of them. (b) The remaining three patients showed a normal Ig synthesis after stimulation with PWM and a slightly depressed IgM synthesis in response to S. aureus. They expressed a normal T helper cell function and did not show increased spontaneous suppressor T cell activity. They had low levels of natural killer cytotoxicity and the OKT4+/OKT8+ ratio was not significantly altered. Taken together, our data indicate that significant alterations of the in vitro immune response can be found in peripheral blood mononuclear cells of some immunoproliferative small intestinal disease patients after long term remission.