Alpha chain disease proteins (ACDP) originated probably from secreting plasma-cells predominantly present in diffuse and massive enteromesenteric lymphoid infiltration. Very decreased levels of abnormal alpha chain molecules were detected in sera of patients with immunoblastic lymphoma occurring in the late course of the disease. A direct correlation might exist between the proportion of cells bearing intracytoplasmic IgA determinants and the serum amounts of alpha chain disease protein. Relevant evidence raised from study of proliferating lymphoid cells using the unlabeled peroxidase anti-peroxidase method of immunocytochemistry. The percentage of cells expressing intracytoplasmic alpha chains was found to be greater readily secreting case than in hyposecreting case of alpha chain disease. Furthermore, the cells from secreting situation exhibited much more pronounced specific staining, indicative of probably more active synthesis state. Taken together with histological data, these results suggested a possible late evolutionary pathway without detectable intracytoplasmic and serum alpha chain disease protein. They might also support the hypothesis that alpha chain disease and mediterranean lymphoma were different evolutionary phases of the same entity.