GENETIC AND IMMUNOLOGICAL MARKERS IN POUCHITIS

Objectives: Previous studies of the interleukin-1 receptor antagonist (IL-1RN) have found an increased frequency of the associated variable number tandem repeat (VNTR) allele 2 for ulcerative colitis (UC) and f urther evidence has been reported that this allele is associated with increased severity of several other inflammatory conditions. The HLA t ype of UC patients has-also been implicated in the extent of disease a s has the presence of perinuclear anti-neutrophil cytoplasmic antibodi es (p-ANCA). We therefore decided to test the hypothesis that the p-AN CA, HLA type or the presence of the IL-1RN allele 2 in patients who re ceived a restorative proctocolectomy for UC had an effect on the risk of developing pouchitis. Patients: We determined the genotypes of the IL-1RN and HLA DR beta and DQ beta loci for 28 subjects with previous UC and a pouch with no evidence of pouchitis for a minimum of 2 years after formation of an ileo-anal reservoir (mean 6.3 years; range 2-17 years) and 25 subjects with previous UC and pouchitis confirmed by str ict histological examination of pouch mucosal biopsy. The IL-1RN genot ypes were also determined for 86 healthy controls and 61 unrelated pat ients with familiar adenomatous polyposis (FAP). The p-ANCA status was determined for all 25 pouchitis subjects but only 23/28 non-pouchitis subjects, with 15 unaffected subjects as a negative control. Methods: The HLA haplotypes of the UC groups were determined by polymerase cha in reaction sequence-specific primer (PCR-SSP) typing and the IL-1RN g enotypes were determined by PCR and agarose gel electrophoresis. The p -ANCA status was determined by indirect immunofluorescence. Results: A chi(2) of 5.686 with 1 degree of freedom and a P value of 0.0171 usin g Yates' correction was obtained by comparing the IL-1RN allele freque ncies of the combined UC groups to the FAP controls, and a chi(2) of 6 .801 with 1 degree of freedom and a P value of 0.0091 comparing the po uchitis group to the FAP controls. The HLA haplotype frequencies did n ot vary significantly between groups nor did they correlate with p-ANC A status. There were also no significant associations of the p-ANCA st atus and pouchitis. Conclusion: There is an increased frequency of IL- 1RN allele 2 in UC, with the majority of the association arising from the pouchitis group, suggesting that the presence of allele 2 in patie nts with UC affects the disease outcome. However, the HLA frequencies and p-ANCA status do not have any significant associations.