Partial purification and biochemical characterization of a T cell suppressor factor produced by human glioblastoma cells.

The human glioblastoma cell line 308 constitutively secretes a soluble factor with biologic and biochemical characteristics of human monocyte-derived interleukin 1 (IL 1). The 308 cells also produce a 97,000 m.w. factor that inhibits the effects of IL 1 and interleukin 2 (IL 2) on T lymphocytes. By using sequential chromatography on Blue Affigel, hydroxyapatite, and Ultrogel AcA54, the inhibitory factor, termed glioblastoma-derived T cell suppressor factor (G-TsF), was separated from IL 1 and purified 2000-fold with respect to the protein present in the crude 308 cell supernatant. This G-TsF preparation was sensitive to tryptic proteolysis, showed a peak of pI 4.6 on isoelectric focusing, and when labeled with 125I, revealed six protein bands in the range of 30 to 100 kdaltons on SDS gel.