Background and aims: CD40/CD40 ligand (CD40L) interaction is important for induction of T cell dependent antibody production and cell-mediated immune responses. Overexpression of CD40/CD40L in the intestinal mucosa is likely to be involved in the pathogenesis of inflammatory bowel disease (IBD). A soluble form of CD40L (sCD40L) exists in the circulation. This study investigated whether plasma levels of sCD40L are higher in patients with IBD than in healthy controls.
Patients and methods: Plasma levels of sCD40L were measured in 89 patients with Crohn's disease (CD), 56 patients with ulcerative colitis (UC), 17 patients with infectious diarrhea, and 42 healthy controls, using a specific enzyme-linked immunosorbent assay.
Results: In CD patients plasma levels of sCD40L were significantly higher than in healthy controls. Patients with UC and infectious diarrhea had higher sCD40L levels than healthy controls, but the differences were not significant. CD patients with fistulas and/or abscesses (n=38) had significantly higher levels of sCD40L than patients with uncomplicated CD (n=51). Only in patients with uncomplicated CD plasma levels of sCD40L correlated significantly with C-reactive protein and alpha(1)-glycoprotein. In UC patients there was a significant correlation of sCD40L with C-reactive protein. However, there was no significant correlation between plasma sCD40L levels and Crohn's disease activity index or Rachmilewitz score.
Conclusion: Elevated plasma levels of sCD40L in CD patients supposedly reflect activation of functional CD40L in the intestine and might be a marker of intestinal inflammation.