BLA.36: a glycoprotein specifically expressed on the surface of Hodgkin's and B cells

Abstract

Anti-BLA.36 is an antibody that recognizes a glycoprotein with an apparent molecular weight of 36 kilodaltons, termed B lymphocyte antigen (BLA.36). By using an immunochemical staining technique, BLA.36 was found to be specifically expressed on Hodgkin's and human B cell lines including early B progenitor cells. Other cell lines representing T cell lymphomas, non-B large cell lymphomas, melanomas and carcinomas were consistently negative. BLA.36 is distinct from the previously identified antigens of hematopoietic cell lineage. The specificity of expression of BLA.36 in tissue sections mirrored that of cell lines. In normal tissues, BLA.36 was detectable predominantly on cells in the germinal center and mantle zone of reactive follicles in lymph nodes and spleens. In hematopoietic malignancy, the antigen was expressed on the surface of Reed-Sternberg cells, mononuclear Hodgkin's cells and also on malignant cells of B cell lineage. BLA.36 was also observed on lymphoid cells of 10 to 24 week fetal liver: a double-antibody-staining method revealed that these BLA.36-positive cells also contained immunoglobulin mu heavy chain consistent with identification as early B cells. Under these conditions, T lymphocytes, histiocytes, granulocytes, macrophages, stromal cells in lymphoid tissue, and both normal and neoplastic epithelial cells were consistently negative for the expression of the antigen, with the single exception of a variable proportion of Kupffer cells in normal liver. The antibody has already established its usefulness for the identification of Reed-Sternberg and Hodgkin's cells, and also normal and malignant B lymphocytes in frozen as well as formalin-fixed tissue sections. Furthermore, binding of F(ab)2 fragments of anti-BLA.36 to antigen-positive cell lines specifically inhibited the proliferation of cells. Such an effect was eliminated by the removal of the antibody from the culture-medium, suggesting a possible growth-related function of the antigen in Hodgkin's and B cells.