CD31 (JC70) EXPRESSION IN PLASMA-CELLS - AN IMMUNOHISTOCHEMICAL ANALYSIS OF REACTIVE AND NEOPLASTIC PLASMA-CELLS

Aims-To investigate the immunohistochemical expression of CD31 (JC70) in normal, and neoplastic plasma cells. Methods-Plasma cells in bone m arrow biopsies and extramedullary locations were examined. All extrame dullary biopsies were formalin fixed and paraffin embedded. The bone m arrow biopsies were fixed in formal acetic acid and embedded in paraff in wax. Twenty multiple myelomas (12 bone marrow and eight extramedull ary deposits), 10 extramedullary plasmacytomas, and 30 biopsies with r eactive plasma cells (10 bone marrow, 20 extramedullary biopsies) were stained with anti-CD31 (JC70) using the streptavidin-biotin detection system with diaminobenzidine as a chromogen. Antigen retrieval in bon e marrow biopsies was achieved by pressure cooking. In all other biops ies, antigen retrieval was achieved by microwave pretreatment. Results -All 20 extramedullary cases with reactive plasma cells showed intense membrane staining. Focal staining was detected in reactive plasma cel ls in bone marrow biopsies. Five of 10 plasmacytomas showed membrane s taining. None of the cases of multiple myeloma, either medullary or ex tramedullary, showed any immunoreactivity for CD31. Conclusions-CD31, a member of the immunoglobulin supergene family of cell adhesion molec ules, is strongly expressed in extramedullary reactive plasma cells, f ocally in bone marrow reactive plasma cells, and occasionally in extra medullary plasmacytomas.