Lamina Propria Mononuclear Cells Express and Respond to Interleukin-2 Differently in Crohn's Disease and Ulcerative Colitis

Lymphokine-activated killer (LAK) cell activity and messenger RNA (mRNA) expression for interleukin-2 (IL-2) were analyzed using lamina propria mononuclear cells (LPMC) in inflammatory bowel disease patients. Compared with control LPMC, Crohn's disease (CD) LPMC exhibited significantly higher levels of LAK cell activity, whereas ulcerative colitis (UC) cells showed significantly lower levels of cytolytic activity with a difference in the frequency of CD3⁺ CD56⁺ and CD3^-, CD56⁺ LAK precursor cells. After incubation with IL-2, the proportion of CD3⁺ CD56⁺ lymphocytes continued to be higher in CD cultures and substantially lower in UC cultures. Freshly isolated CD LPMC exhibited significantly higher levels of IL-2 mRNA than controls. However, no significant difference was observed between UC and control cells. The level of IL-2 expression or responsiveness to IL-2 may be responsible for different mucosal immune reactivity between CD and UC patients.