Antireticulin antibodies in collagenous and lymphocytic (microscopic) colitis.

Serum antireticulin antibodies (ARAs) are often present in patients with dermatitis herpetiformis and celiac disease (CD), especially before instituting a gluten-free diet. In both collagenous colitis (CC) and lymphocytic (microscopic) colitis (LC) the colorectal mucosa shows surface epithelial damage with intraepithelial lymphocytes that is strikingly comparable to the small intestinal findings in CD. Also, CD may show subepithelial collagen deposition resembling that seen in CC. Because of these similarities, ARAs were measured in sera from patients with biopsy-proven CC and LC and compared with sera tested from CD patients. Antibody binding to reticulin was detected in frozen sections of rat liver and kidney by indirect immunofluorescent techniques. Whereas five of 14 CD patients (35.7%) had ARAs, only one of 29 CC patients (3.4%) (P = 0.010 versus CD) and none of 17 LC patients (0%) (P = 0.012 versus CD) had ARAs. The positive CC patient had IgA ARA titers of 1:20 noted in two sera taken 2 mo apart. The five positive CD patients had IgA ARA titers ranging from 1:20 to 1:320. The rare presence of ARAs noted in collagenous colitis and lymphocytic colitis was similar to its occurrence in normals, whereas the frequency of ARAs found in celiac disease (35.7%) was within the range reported for that disorder. Therefore, ARAs do not appear to be associated with CC or LC despite the morphologic similarities to CD.