Histopathologic changes and the immune response within the jejunal mucosa in infants and children.

Jejunal biopsies obtained from 45 children referred for a variety of clinical conditions were examined histologically and by standard immunofluorescence methods. The number of plasma cells was recorded per "mucosal tissue unit". The results showed that most of the immunoglobulin A (IgA) counts in infants under 3 yr with normal mucosa were low and that there was a rise in the number of IgA plasma cells starting after this age. Despite this, under pathologic conditions (partial villous atrophy with increased inflammatory cell infiltration--PVA) a significant rise in IgA plasma cells occurred in all age groups. Patients with coeliac disease tended to show the highest IgA as well as IgM plasma cell counts. In all other patients, IgM counts did not change significantly with age or histologic abnormalities.