Patients with Hodgkin's disease, either untreated or in remission, exhibit a persistent defect in cellular immunity. This cellular immune defect appears to be the result of increased sensitivity to suppressor monocytes and T-suppressor cells, in addition to abnormal Interleukin-2 production. T-lymphocyte function is abnormal in patients with advanced disease. The precise origin of Reed-Sternberg and Hodgkin's cells is unknown. Reed-Sternberg cells function as antigen-presenting cells and as accessory cells in mitogen-induced T-cell proliferation. They have properties in common with dendritic cells and activated lymphocytes. L428 cells express a transformation-associated phosphorylated transmembrane protein, with properties of a growth factor receptor, that may play a role in tumorigenic transformation.