Enhanced interferon-gamma production and B7-2 expression in isolated intestinal mononuclear cells from patients with Crohn's disease.

Many of the in vivo activities of interferon (IFN)-gamma match the changes found in inflammatory bowel disease, but its importance is controversial. Interferon (IFN)-gamma induces the expression of B7-2 costimulatory molecules on monocytes. We measured levels of IFN-gamma production in intestinal mucosa and isolated lamina propria mononuclear cells (LPMC) in patients with Crohn's disease (CD) and ulcerative colitis (UC). We also investigated the induction of B7-2 on the LPMC by flow cytometry. Mucosal IFN-gamma production was higher than the control level in patients with CD, but this was not the case in UC. IFN-gamma production and B7-2 expression in the LPMC of CD were higher than in the LPMC of UC and controls, and high levels of B7-2 expression were observed on the LPMC of CD after incubation with endotoxin. The induction of B7-2 on the LPMC of CD may provide a mechanism for the amplification of T cell proliferation and lymphokine production by IFN-gamma-activated LPMC.