Immunosuppressive acidic protein in true histiocytic lymphoma

Serum immunosuppressive acidic protein (IAP) was determined in patient with true histiocytic lymphoma. The change of serum level of IAP correlated well with the clinical course, i.e., increased at relapse and decreased during remission. Immunohistochemistry showed IAP was present in the cytoplasms of normal granulocytes and histiocytes but not in neoplastic histiocytes.