Demonstration of Crohn's disease tissue-specific proteins by enzyme-linked immunosorbent assay (ELISA)

Theories on the etiology of Crohn's disease have included extrinsic agents and intrinsic bowel wall defects. We sought to determine the presence of immunoreactive antigens specific to Crohn's disease tissue by modifying the enzyme-linked immunosorbent assay. Tissue proteins were extracted from four patients with Crohn's disease and from four normal segments of colon from patients with colonic cancer. These tissue extracts were further purified on Con A Sepharose 4B affinity column. The glycoproteins eluted from this column were adsorbed by polystyrene plates as antigen and tested against 85 sera from patients with Crohn's disease, ulcerative colitis, other diarrheal diseases, and normal subjects. Sera from 48 patients with Crohn's disease showed significantly greater recognition of Crohn's disease tissue glycoproteins than sera from 27 disease controls (P<0.0125) and 10 normal subjects. These Crohn's disease sera also showed preferential recognition of glycoproteins extracted from Crohn's disease tissue compared to glycoproteins from normal colonic tissue (P<0.0005). The nature of these immunoreactive proteins, whether extrinsic or intrinsic, is not yet known. The ELISA may help in further characterization of Crohn's disease tissue-specific glycoprotein(s) and to develop a clinically useful serological test.