Light chain type ratio of IgA-producing cells in human jejunal biopsies.

As part of an investigation on a possible relationship between the serum IgA and the immunoglobulins synthesized by the plasma cells in the intestinal mucosa, immunoglobulin-producing cells in human jejunal biopsies were characterized by class and type of intracellular immunoglobulins. In biopsy Specimens from 22 patients, with various diagnoses except multiple myeloma, the average percentage of IgA-producing cells was 83 percent, that of IgG-producing cells 5 percent and that of IgM-producing cells 12 percent, with a wide range for individual patients. For the IgA-producing cells the kappa/lambda ratio was determined and the average ratio was found to be 63 : 37, within a very limited range for individual patients. There was no correlation between the relative number of IgA-producing cells in the biopsy specimens and the IgA concentration in the serum. Additionally biopsy specimens from 3 patients with a monoclonal immunoglobulin-A component in their serum were studied. In one of those there was a remarkable shift in the kappa/lambda ratio, indicating that the light chain distribution of the intestinal IgA plasma cells was affected by the lympho-proliferative process.