Abstract

Previous investigations of immune function in patients with Crohn's disease have yielded conflicting results. A comprehensive study of immune competence—peripheral lymphocyte count, serum immunoglobulin levels (IgG, IgA and IgM), lymphocyte response to PHA, Mantoux test, and DNCB response—has been performed in a large number of patients with inflammatory bowel disease. A total of 52 patients with Crohn's disease, 20 patients with ulcerative colitis, and 46 control patients with benign gastrointestinal disease were investigated. The patient groups were subdivided into `well' and `ill' in view of the differing clinical states of patients with inflammatory bowel disease. Some of the Crohn's and colitis patients were receiving steroid therapy.

The peripheral blood lymphocyte count and lymphocyte response to PHA were similar in all patient groups. Serum IgA levels were elevated in Crohn's disease but fell significantly in `ill' Crohn's patients following excisional surgery. Serum IgM levels rose significantly in `ill' Crohn's patients after surgery. Steroid therapy was associated with diminution of both Mantoux and DNCB responses in the `ill' Crohn's patients. There was no evidence of impairment of immune competence in either Crohn's disease or ulcerative colitis.