Tumor-associated antigens in human myeloma

Antiserum was generated in rabbits to the RPMI 8226 tissue culture line of human myeloma cells, and its reactions with fixed smears of bone marrow aspirates from patients with multiple myeloma, macroglobulinemia, benign monoclonal gammopathy (BMG), leukemia, and nonneoplastic plasmacyosis was assessed by indirect immunofluorescence. After absorption with preparations of bone marrow from normal individuals, the antiserum reacted to a significantly higher titer with a specific subpopulation of plasma cells in smears from 81% of patients having multiple myeloma and 50% of patients having BMG than with cells in smears of bone marrow aspirates from normal individuals or patients having leukemia or nonneoplastic plasmacytosis, or than with cells in smears of peripheral blood from patients having Hodgkin's and non-Hodgkin's lymphoma. Absorption of the antiserum with RPMI 8226 cells or with a bone marrow preparation from a patient with multiple myeloma but not the Jijoye line of Burkitt's lymphoma reduced reactivity for cells in myeloma bone marrow. The antiserum reacted at a lower titer with the Jijoye and EB-3 lines of Burkitt's lymphoma, the RPMI 4098 cell line of normal human lymphocytes, and culture lines of human melanoma and osteogenic sarcoma than with the RPMI 8226 cells or bone marrow from certain patients having multiple myeloma. Approximately 50% of the cells reactive with antiserum to RPMI 8226 cells in the bone marrow of patients with multiple myeloma were not producing immunoglobulin, as assessed by double immunofluorescence assay. The data suggested that a subpopulation of plasma cells in the bone marrow of patients with multiple myeloma possesses a tumor-associated antigen.