Neoplastic cells obtained from Hodgkin's disease are potent stimulators of human primary mixed lymphocyte cultures.

Neoplastic cells obtained from the pleural effusion of a patient with Hodgkin's disease have been maintained in culture since 1978. These tumor cells have been shown to have the cytologic features, cytochemical staining, and cell surface markers of Reed-Sternberg cells. In this study we demonstrate that the cell line termed L428 is a potent stimulator of the primary human mixed lymphocyte reaction. Significant proliferation occurred when mononuclear leukocytes obtained from normal donors were stimulated with radiated L428 cells at responder:stimulator ratios varying from 200:1 to 20:1. Proliferative responses occurred between days 3 and 6 of the cultures with maximal proliferation on day 5. Under optimal culture conditions, mean net proliferative response of 14 normal donors was 51,000 +/- 10,600 dpm. The mixed lymphocyte response was totally blocked by concentrations of monoclonal anti-Ia antibody that had no effect on concanavalin A-induced proliferation. However, the mixed lymphocyte response was not blocked by an anti-K562 cell monoclonal antibody of the same immunoglobulin subclass that binds to the L428 cells. Antigen processing by responder monocytes or Ia-positive cells was not required for the MLC. When responder T cells from two normals were depleted of Ia-bearing cells and monocytes, the mixed lymphocyte reaction between the two normals was eliminated, yet the stimulation of each normal by the L428 cells was not reduced. The cells that proliferated in response to stimulation by the L428 cells were T cells, primarily of the helper subset. No IL 1 activity could be detected in concentrated supernatants of L428 cultures after stimulation of L428 cells by mitogens, phorbol esters, or muramyl dipeptide, or in the MLC. All of these cultures contain fetal calf serum. However, the L428 cells are capable of producing IL 1, because IL 1 was detected when the L428 cells were stimulated with LPS in the absence of fetal calf serum. These neoplastic cells, obtained from Hodgkin's disease, have many similarities to the murine as well as human dendritic cells.