Granulocyte colony formation in vitro: Enhancement by human placental (umbilical cord) serum

Summary Addition of human placental umbilical cord serum to bone marrow cultures reproducibly increased the number of granulocyte colonies in vitro. This stimulatory effect was significantly greater than that of fetal calf serum which was seen in cultures of human bone marrow under the conditions described.This work was financed by grant FOR. No. 004.AK.71 (1) from the Swiss Cancer League.The authors wish to express their gratitute to colleagues from Maternity Ward, Frauenspital, Bern, and Department of Thoracic and Vascular Surgery, Inselspital, Bern, through whose kind assistance samples of umbilical blood and fragments of ribs removed at thotacotomies were obtained. MissJ. Blom provided excellent technical assistance.