Cellular distribution of a B-cell specific surface antigen (gp54) detected by a monoclonal antibody (anti-BL4)

A monoclonal antibody (anti-BL4) recognizing a previously characterized Mr 54,000 glycoprotein (gp54) was developed by immunizing BALB/c mice with cells from a precursor B-cell line (Josh-7). In normal individuals, this antigenic molecule was present on tonsillar B-cells (60-80%) and on a fraction of peripheral blood B-cells (5-25%). BL4 (gp54) expression was investigated in 186 patients with a variety of hematological malignancies using indirect immunofluorescence and flow cytometric analysis. Twenty-six of 37 cases of B-cell chronic lymphocytic leukemia (CLL) and 18 of 33 cases of B-cell non-Hodgkin's lymphoma were BL4 positive. Surface expression of BL4 on reactive cases of CLL and non-Hodgkin's lymphoma was brighter than those of B1, B2, and B4, BL4 positive CLL cases expressed a higher proportion of mouse rosette forming cells and Leu-1 positive cells than the BL4 negative subgroup and were not associated with elevated serum immunoglobulin levels. Four of 7 BL4 negative CLL cases were associated with increased serum levels of immunoglobulin M. Lymphoblasts from 14 of 14 cases of non-T acute lymphoblastic leukemia and 3 of 3 pre-B lymphoid blast crisis of chronic myeloid leukemia were BL4 negative. Neoplastic cells from 2 of 3 cases of Waldenstrom's macroglobulinemia and 4 of 7 cases of hairy cell leukemia were BL4 reactive. None of 7 cases of multiple myeloma and plasma cell leukemia were BL4 positive. All 11 T acute lymphoblastic leukemia cases, 6 other T-cell malignancies, 5 cases of Hodgkin's disease, 51 cases of acute nonlymphocytic leukemia, and 9 cases of chronic myeloid leukemia in chronic phase thus far studied were BL4 negative. An in vitro induction experiment using phorbol ester on a case of B-CLL demonstrated disappearance of BL4 accompanied with further B-cell differentiation. Our study further substantiates the previous finding that gp54 is a differentiation antigen restricted to the B-cell lineage and expressed during the intermediate stage of B-cell ontogeny.