Digestive Diseases and Sciences, Vol. 34, No. 10 (October 1989), pp. 1528-1535 Vasoactive Intestinal Peptide as a Laboratory Supplement to Clinical Activity Index in Inflammatory Bowel Disease LINDA C. DUFFY, PhD, MARIA A. ZIELEZNY, PhD, MARIE RIEPENHOFF-TALTY, PhD, TIM E. BYERS, MD, MPH, JAMES MARSHALL, PhD, MILTON M. WEISER, MD, SAXON GRAHAM, PhD, and PEARAY L. OGRA, MD Circulating levels of vasoactive intestinal peptide (VIP) in plasma were measured in gauging activity in inflammatory bowel disease (IBD). One hundred-fifteen adult IBD patients were studied cross-sectionally and prospectively, 48 with ulcerative colitis (UC) and 67 with Crohn's disease (CD). Sequential samples of plasma were assayed for VIP by specific radioimmunoassay. Sbcty males and 55 females, ranging in age from 22 to 76 years were studied over six months. The results revealed a strong, positive association between VIP levels and clinical activity, both at baseline (r = 0.38, P < 0.001) and follow-up (r = .41, P < 0.001). The ability of the VIP immunoassay to gauge clinical activity was also evaluated where VIP concentrations above 30 pg/ml were defined as abnormal. At baseline, sensitivity (specificity) was found to be 81% (55%). The predictive value of a positive (negative) test was 57% (80%). These estimates did not differ at follow-up. Examination of paired plasma samples from intermittently active patients revealed nearly twofold increases (P < 0.05) in VIP concentration during active periods of disease. The data suggest that plasma VIP levels may be a valuable laboratory parameter in gauging activity in inflammatory bowel disease. KEY WORDS: disease activity; inflammatory bowel disease; vasoactive intestinal peptide; sensitivity; specificity. Manuscript received December 28, 1988; revised manuscript received May 22, 1989; accepted May 23, 1989. From the Department of Pediatrics, Microbiology, Children's Hospital, School of Medicine; Department of Social and Preven- tive Medicine; Division of Gastroenterology, Hepatology and Nutrition, State University of New York; the Buffalo General Hospital, Buffalo New York; and Office of Epidemiology, New Mexico State Department of Health and Environment, Sante Fe, New Mexico. Supported by research grants AI 15939-08, National Institute of Allergy and Infectious Diseases; HD 19679-02, National Institute of Child Health and Human Development; and CA 09051, National Cancer Institute, Department of Health and Human Services. The research herein was presented, in part, at the Federation of American Societies for Experimental Biology (FASEB) in Las Vegas, Nevada, May 1988. Address for reprint requests: Linda C. Duffy, PhD, Epidemi- ology and Biostatistics Research Office, Children's Hospital, Buffalo, New York 14222. Recent advances in immunochemistry have helped to establish that the intestinal circulation is sub- jected to neurogenic inflammation elicited by acti- vation and release of peptide mediators from enteric nerve endings (1). Vasoactive intestinal peptide (VIP), widely distributed throughout the human digestive tract and central nervous system, is thought to be involved in major physiologic pro- cesses of the intestine and other body organs (2). O'Dorisio et al (3) reported that human peripheral blood lymphocytes possess receptors for VIP that appear to stimulate adenylate cyclase. One of the most recognized pathologic involvements of VIP is its association with the cholera-like symptoms of 1528 Digestive Diseases and Sciences, Vol. 34, No. 10 (October 1989) 0163-2116/89/1000-1528506.00/0 9 1989 PlenumPublishingCorporation