Chalone-like effect abrogated by dextran sulphate and heparin polyanion pretreatment of target cells.

Chalone prepared from primary BALB/c mouse embryo fibroblasts caused a 33% reduction in incorporation of tritiated thymidine in the cultures of the second in vitro passage of BALB/c embryo fibroblasts, whereas chalone prepared from thymus, skin and spleen was without effect. Pretreatment of BALB/c secondary fibroblasts with the polyanions dextran sulphate and heparin abrogated the chalone effect. The polycations DEAE-dextran and polybrene were without effect. The effect of incubation with the dextran sulphate polyanion was reversed when followed by incubation with DEAE-dextran polycation.