Induction of giant fat cells in human bone marrow culture by human serum factor

Evidence is presented below that normal human sera contain a potent non-dialyzable factor inducing abundant giant fat cells in human bone marrow culture, normal as well as CML. Media with 20% heated (56 degrees C) human serum induce during 7-14 days almost complete monolayer of fat cells on the bottom of the plastic flasks or dishes. Fetal bovine sera do not exhibit this effect and shift cultures to the proliferation of fibroblasts. We are studying the functions of fat cells in hemopoiesis as well as the biochemical nature of fat cell-inducing factor in human sera.