ANTINEUTROPHIL CYTOPLASMIC ANTIBODIES IN INFLAMMATORY BOWEL-DISEASE WITH SPECIAL ATTENTION FOR IGA-CLASS ANTIBODIES

Perinuclear anti-neutrophil cytoplasmic antibodies (P-ANCA) of the IgG class have been reported in inflammatory bowel disease, mainly in ulc erative colitis. Since this disease affects the gastrointestinal tract , we determined whether IgA class ANCA were present in inflammatory bo wel disease. We used an indirect immunofluorescence assay for IgG and IgA ANCA testing. Sera from 34 patients with Crohn's disease and 29 pa tients with ulcerative colitis were collected together with clinical a nd laboratory data. We found IgA class ANCA of a perinuclear type in 5 2% of patients with ulcerative colitis and in 9% of Crohn's disease pa tients. There was a significant association between the presence of Ig A ANCA and the occurrence of blood in the feces in the ulcerative coli tis group (P = 0.03). IgG ANCA was found in 56% of patients with ulcer ative colitis and in 7% of patients with Crohn's disease. Because of p artial overlap between IgG and IgA ANCA positivity, the sensitivity of ANCA testing in ulcerative colitis increased from 56% up to 78% by co mbining IgG and IgA assays. In conclusion, IgA ANCA occurs with a high prevalence in ulcerative colitis. Moreover there is a possible relati onship between IgA ANCA and disease activity in ulcerative colitis.