Anti-immunoglobulins in multiple myeloma

Human myeloma cells isolated from bone marrow aspirates by sucrose density gradients and cultured in vitro were shown to undergo proliferation and increased DNA synthesis upon incubation with anti-immunoglobulin (anti-Ig) antisera directed against the immunoglobulin that these cells carry or secrete. A circulating anti-Ig could be detected in the sera of the majority of these patients. In a γ-globulin-free medium, the isolated anti-Ig could stimulate the patient's own plasma cells to undergo proliferation in vitro. The possible role of circulating anti-Ig in the in vivo continued proliferation of a specific clone of bone marrow cells is discussed.