Labile inhibitor of lymphocyte transformation in plasma from a patient and subacute sclerosing panencephalitis.

A thermolabile inhibitory factor of mitogen-induced lymphocyte transformation was observed in the fresh plasma of one patient in stage 3 of subacute sclerosing panencephalitis (SSPE) and not in three other patients in various stages of the disease. Thus, its relevance to SSPE is not clear. The plasma factor was removed by adsorption onto human and animal cells and polystyrene beads, and it was found in the 7S globulin fraction of the effluent from gel permeation chromatography.