Blood Journal
Leading the way in experimental and clinical research in hematology

A New Human Low Molecular Weight Granulocyte Colony Stimulating Activity

  1. G. B. Price, Ph.D., Post-doctoral Fellow of The Damon Runyon Memorial Fund,
  2. E. A. McCulloch, M.D., F.R.C.P. (C), and
  3. J. E. Till, Ph.D.
  1. The Ontario Cancer Institute and Departments of Medicine and Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.
  2. Ontario Cancer Institute, Toronto, Canada.
  3. Department of Medicine, University of Toronto, and the Ontario Cancer Institute, Toronto, Canada.
  4. Department of Medical Biophysics, University of Toronto, and the Ontario Cancer Institute, Toronto, Canada.

Abstract

Fractionation of conditioned medium derived from cultures of human peripheral blood leukocytes by ultrafiltration yielded material of low molecular weight, capable of stimulating the formation of granulopoietic colonies by human marrow cells in culture. The molecular weight of the active material was found to be less than that of vitamin B12 (1330 mol wt) on the basis of gel filtration on Sephadex G-25. The low molecular weight colony-stimulating activity (LMW-CSA) was trypsin-sensitive, and extractable into chloroform or diethyl ether. Unlike unfractionated leukocyte-conditioned medium, the LMW-CSA showed no colony-stimulating activity when tested on mouse, rather than human, marrow cell cultures.

  • Submitted November 20, 1972.
  • Revision received January 29, 1973.
  • Accepted February 20, 1973.