Further purification of a tissue specific inhibitor in lymphopoiesis (lymphocyte chalone?)

Abstract

A partially purified calf spleen extract, which exhibits the properties of a lymphocyte chalone (tissue-specific, species non-specific, non-toxic and reversible acting, endogenous inhibitor of cell proliferation) as concerning biological activities, has been described earlier. This fraction has been further purified by ion exchange chromatography with DEAE-Sephacel to a 10,000-fold purification. The most active fraction inhibited 3H-thymidine incorporation into phytohemagglutinin- or pokeweed-mitogen-stimulated lymphocytes by 86% resp. 70%, when given in a concentration of 100 ng/ml. Ehrlich-ascites-cells were not inhibited by the same concentration. The inhibiting activity is compared to other published lymphocyte inhibitors.