Immunoproliferative small intestinal disease in Algerians. I. Light microscopic and immunochemical studies.

Twenty-two cases of immunoproliferative small intestinal disease (IPSID) were studied with an immunoperoxidase technique. Sixteen of these had serologic evidence of alpha heavy chain disease (AHCD) and have a characteristic immunochemical pattern that allows a diagnosis on jejunal biopsy. kappa-light chain was found in a case of AHCD in the benign appearing plasma cell proliferation and in the associated malignant lymphoma suggesting that failure of light chains is not constant in AHCD. Four cases of IPSID showed secretion of polyclonal IgA in the plasma cell infiltrate providing evidence that some cases may be associated with secretion of complete IgA molecules. This polyclonal pattern is suggestive of a reactive process. Two cases of IPSID without evidence of AHCD showed an immunohistochemical pattern characteristic of AHCD and may represent nonsecreting forms of the disease. Alternatively they may be secreting nondetectable amounts of AHCD protein or an abnormal protein not recognized by standard antisera.