Immunoglobulin G subclass distribution of anti-endothelial cell antibodies (AECA) in patients with ulcerative colitis or Crohn's disease.

Anti-endothelial cell antibodies have been described in sera from patients with inflammatory bowel disease. The aim of this study was to determine, by ELISA, the IgG subclass distribution of anti-endothelial cell antibodies, in patients with ulcerative colitis (N = 28) or Crohn's disease (N = 82) as compared with blood donors (N = 95). Thirty-six percent of ulcerative colitis and 23% of Crohn's disease patients were positive for at least one of the IgG anti-endothelial cell subclasses. Interestingly, the pattern of IgG anti-endothelial cell subclass observed in the two inflammatory bowel diseases differs. In Crohn's disease, the IgG1 anti-endothelial cell antibody level was significantly increased (P < 0.05) while IgG2 and IgG4 anti-endothelial cell antibody levels were decreased (P < 0.0001 and P < 0.01, respectively) as compared to ulcerative colitis patients. The immunoglobulin G3 anti-endothelial cell antibody level was decreased in both ulcerative colitis and Crohn's disease patients as compared to healthy blood donors. No relationship was detected between disease activity of ulcerative colitis or Crohn's disease patients and anti-endothelial cell IgG subclasses. Finally, the disparity of IgG anti-endothelial cell subclass distribution in these two inflammatory bowel diseases suggests that the ability to activate effector mechanisms is not identical, and hence, deals with the concept of distinctive pathogenetic mechanisms in these two diseases.