Immunological and biochemical studies of an unusual alpha heavy chain protein in a 9-year-old boy.

Protein electrophoresis in a 9-yr-old Libyan boy suffering from intestinal alpha chain disease showed a conspicuous peak in the gamma region. Examination in immunoelectrophoresis with monospecific antisera against IgA revealed a quantitatively important monoclonal gradient. The heavy chain protein in serum, urine and duodenal juice was further analysed immunologically in double diffusion, antigen-antibody crossed electrophoresis and biochemically in gel filtration experiments and SDS PAGE. By these techniques alpha 1 chain aggregates of different molecular weight could be found. Immunofluorescence examination of small intestine biopsies showed abundant plasma cells containing alpha heavy chains but no light chains.