Raised concentrations of platelet activating factor in colonic mucosa of Crohn's disease patients.

Platelet activating factor (PAF-ACETHER or PAF) and precursors of platelet activating factor were investigated in 26 patients with acute Crohn's disease and in 10 healthy controls. Platelet activating factor, lyso platelet activating factor, and alkyl acyl glycerophosphocholine, were determined in colonic mucosal biopsies in patients with acute Crohn's disease, during prednisolone therapy, and in remission. Biopsy specimens were submitted to histopathology examination and to phospholipid extraction. Platelet activating factor, lyso platelet activating factor, and alkyl acyl glycerophosphocholine were found in patients with acute Crohn's disease and in remission as well as in controls. Whatever the site of the biopsy, the level of platelet activating factor in colonic mucosa was higher (p < 0.01) in Crohn's disease than in controls. There was no correlation between the level of colonic PAF-ACETHER and age, sex, Crohn's disease activity index, and biological parameters in sera. Although concentrations of colonic platelet activating factor content were higher (p < 0.01) when colonic mucosa displayed cell infiltration, they were neither related to the severity nor the type of inflammatory cells. Platelet activating factor decreases with prednisolone therapy and might return to normal concentrations in quiescent patients. Lyso platelet activating factor and alkyl acyl glycerophosphocholine were not significantly higher in Crohn's disease than in controls. These data suggest that platelet activating factor may be involved in the pathogenesis of Crohn's disease and that it could be used as a marker of the mucosal activity of the disease.