Distribution of cells containing different IgG and IgA subclasses in the colonic mucosa in childhood ulcerative colitis and Crohn disease

The distribution of cells containing various subclasses of IgG and IgA were studied in the rectal and colonic mucosa from 14 paediatric patients with ulcerative colitis and four patients with Crohn's disease, as well as, from rectal biopsy specimens of 10 control subjects using monoclonal antibodies and the peroxidase method. The number of IgG3-containing cells in both the colonic and rectal mucosae of untreated patients with ulcerative colitis was significantly increased compared to controls. In the children with ulcerative colitis the number of IgG4 cells in the colonic mucosa was also significantly increased. In the rectal mucosa of patients with ulcerative colitis the percentage of IgG2 cells was decreased compared to the controls (22% versus 27%). In the great majority of specimens (in 37 out of 40) the number of IgA1 cells was higher than that of IgA2. The number of IgA1 cells in the rectal and colonic specimens of untreated patients with ulcerative colitis was slightly higher than that in the rectal specimens of controls. Authors speculate on the basis of their results that the observed IgG3 response in the patients with ulcerative colitis may be specific to the disease.