Isolation and characterization of cytotoxic effector cells and antibody producing cells from human intestine.

We have examined the ability of intestinal and peripheral blood mononuclear cells isolated from patients with inflammatory bowel disease to mediate killing against cell line targets in spontaneous, antibody-dependent, lectin-induced, and interferon-induced cell-mediated cytotoxicity assays, as well as responsiveness in the allogeneic mixed leukocyte reaction, and effector capabilities in cell-mediated lympholysis. IMC were poor mediators of spontaneous or antibody-dependent cellular cytotoxicity with cell line cells as targets (in comparison to normal PBMC, but were capable of killing antibody coated chicken red blood cells. Although IMC were capable of responding to allogeneic cell surface antigens in the mixed leukocyte reaction, they did not exhibit effector function in cell-mediated lympholysis. Mitogenic lectins induced cell-mediated cytotoxicity by isolated intestinal mononuclear cells from controls and patients. HFIF induces cytotoxicity by control but not inflammatory bowel disease intestinal cells. Pokeweed mitogen was the lectin which induced the greatest amount of killing against human cell line targets. We therefore speculate that exogenous agents, or endogenous factors released during viral infection, could play a role in inducing cell mediated cytotoxic damage to the intestine in inflammatory bowel disease patients. In addition, the functional differences between IMC and PBMC indicate that intestinal MNC may have unique cell capabilities which must be better understood prior to the delineation of immunopathologic events in solid organ tissues. We have also examined the secretion of IgA, IgM, and IgG by isolated human IMC, human bone marrow MNC from rib specimens, and PBMC from patients with CD, UC, SLE, or Henoch-Schoenlein purpura (HSP). Control IMC exhibited high spontaneous secretion of IgA, while intestinal MNC from UC and CD patients exhibited only modest increases in IgA secretion. PBMC from patients with CD, UC, SLE, or HSP exhibited markedly elevated spontaneous secretion of immunoglobulins in general and IgA in particular. Pure human bone marrow MNC exhibited high spontaneous secretion of IgA, and modest amounts of IgG and normal IgM secreting. The addition of PWM to cultures exhibiting high spontaneous synthesis and secretion of immunoglobulins resulted not in further enhancement but in suppression of antibody secretion. The characterization of types of IgA secreted by human IMC revealed that normal human bone marrow secretes almost exclusively monomeric IgA, while control human intestine secretes predominantly dimeric IgA. IMC from patients with CD and non-involved UC specimens also secreted predominantly dimeric IgA.(ABSTRACT TRUNCATED AT 400 WORDS)