CONCENTRATIONS OF PLATELET-ACTIVATING-FACTOR IN RECTAL MUCOSA IN PATIENTS WITH ULCERATIVE-COLITIS

Objective: To find out if concentrations of platelet activating factor (PAF), which has been proposed as a mediator in the pathogenesis of u lcerative colitis and Crohn's disease, are increased in the rectal muc osa of patients with ulcerative colitis. Design: Open study. Setting: University hospital, Sweden. Subjects: 45 Patients with ulcerative col itis (19 with active disease and 26 in remission), and 6 control patie nts and 11 healthy volunteers who acted as controls. Interventions: Re ctal biopsy. Main outcome measure: PAF content of rectal biopsy specim ens. Results: There were no differences between the PAF content of rec tal mucosa in patients with active disease (median 47 pmol/g wet weigh t), patients in remission (47 pmol/g), and controls (51 pmol/g). There was no correlation between PAF content and inflammation seen endoscop ically or histologically. 13 Patients who had active disease were inve stigated on a second occasion 9 weeks later (range 7-17), when in remi ssion having received steroids but steroid-free at that time. There wa s a slight but not significant trend towards lower concentrations of P AF (median 33 pmol/g) compared with their previous results, possibly a s a result of treatment. PAF concentrations were significantly lower t han those of a group of patients in clinically stable remission of lon ger duration (p < 0.05). Conclusions: We did not find high concentrati ons of PAF in the rectal mucosa of patients with active ulcerative col itis compared with patients in remission or controls. We therefore hav e no evidence that PAF has an important role as a mediator in the infl ammation of ulcerative colitis.