Glia cell stimulating factor (GSF): a new lymphokine. Part 2. Cellular sources and partial purification of human GSF

Glia cell proliferation is characteristic of many inflammatory and degenerative processes in the brain, however the mechanisms underlying this response are poorly understood. We described a glia cell stimulating factor (GSF), produced by murine spleen cells, which activates DNA- and RNA synthesis of cultured glia cells. In the present series of experiments, we examined the ability of Concanavalin A (ConA)-stimulated human peripheral blood mononuclear leukocytes (PBM) and two continuous cell lines derived from human lymphocytes to spontaneously release of GSF in culture. The studies presented herein demonstrate that (1) ConA-stimulated PBM of healthy subjects produced GSF, (2) GSF is produced by T lymphocytes in collaboration with monocyte-macrophages, (3) both the human T cell line (MOLT-4F) and a B cell line (RPMI 1788) spontaneously secrete GSF, (4) GSF was found to have a molecular weight of 30,000 and less than 10,000 daltons, (5) macrophage (MIF)- and leukocyte (LIF) migration-inhibiting factor activities, as well as mitogenic factor (MF)- and lymphocyte-activation factor (LAF) activities could be separated from the GSF activity by gel filtration on Biogel P-100. These findings provide further evidence for the existence of GSF as a new lymphokine, distinct from LIF, MIF, MF and LAF.