Described herein is a large-scale procedure that has been successfully employed for producing 62 lots (800-3000 ml) of supernatants containing the T cell growth-promoting factor Interleukin-2 (IL-2). The efficiency of these crude, unconcentrated supernatants was documented in studies in which 70 human long-term (greater than 100 days) IL-2-dependent T cell lines were established from 50 different donors. These included lines initiated from the peripheral blood of healthy subjects (N = 54), blood of children with active acute lymphoblastic leukemia (N = 6) and the thymus of children undergoing surgery to correct congenital heart defects (N = 10). The underlying concept used in constructing this method emphasizes the requirement of the monocyte-derived macrophage and its Interleukin-1 (IL-1) product to mediate IL-2 production by activated T cells. The most salient feature of this technique is the utilization of buffy coat leukocytes that had been pooled from several blood donors and sustained in spinner cultures for several days prior to polyclonal activation with phytohemagglutinin and pooled B cells of established human lymphoblastoid lines.