Middle East lymphoma and alpha-chain disease. An immunohistochemical study.

An immunoperoxidase study of the small intestinal mucosa of three patients with alpha-chain disease showed heavy infiltration of the mucosa by plasma cells containing alpha-heavy chain and J-chain but no light chains. An additional band-like and nodular mucosal infiltrate was also present and consisted of cells showing no evidence of cytoplasmic immunoglobulin synthesis. The cells comprising this infiltrate invaded and destroyed intestinal crypts, and immunoperoxidase staining showed them to be sharply distinct from the alpha-chain-containing plasma cells. In two cases of Middle East lymphoma, immunohistochemistry revealed a normal plasma cell population in the lamina propria of the small intestine. These results show that alpha-chain disease can be diagnosed in routine paraffin sections which should permit clarification of its true incidence in Middle East lymphoma. The demonstration of sharp distinction between the two types of mucosal infiltrate in alpha-chain disease is in contrast to previous immunofluorescence results and enables more ready identification of mucosal changes that may be important in the management of the disease.