Human serum megakaryocyte colony-stimulating activity appears to be
distinct from interleukin-3, granulocyte-macrophage colony-stimulating
factor, and lymphocyte-conditioned medium
EM Mazur, JL Cohen, J Newton, P Sohl, A Narendran, TG Gesner and RA Mufson
Department of Medicine, Miriam Hospital, Providence, RI 02906.
Sera from patients with bone marrow megakaryocyte aplasia are a rich source
of megakaryocyte colony-stimulating activity (Meg-CSA). Other biologic
materials exhibiting Meg-CSA include phytohemagglutinin- stimulated human
lymphocyte-conditioned medium (PHA-LCM), recombinant interleukin-3 (IL-3),
and recombinant granulocyte macrophage colony- stimulating factor (GM-CSF).
Neutralizing antisera to both recombinant IL-3 and GM-CSF were used to
evaluate the relationship among these sources of Meg-CSA. Varying dilutions
of IL-3 and GM-CSF antisera were tested in plasma clot cultures of normal
human peripheral blood megakaryocyte progenitors optimally stimulated by
either IL-3 (1 U/mL), GM-CSF (1 U/mL), PHA-LCM (2.5% to 5% vol/vol), or
aplastic human serum (10% vol/vol). IL-3 antiserum at dilutions up to
1/2,000 totally abrogated megakaryocyte colony growth stimulated by IL-3. A
1/500 dilution of GM-CSF antiserum completely eliminated GM-CSF-induced
megakaryocyte colony development. A combination of anti-IL-3 and anti-
GM-CSF, each at a 1/500 dilution, inhibited all megakaryocyte colony growth
stimulated by optimal concentrations of IL-3 and GM-CSF together. There was
no neutralizing crossreactivity between the IL-3 and GM-CSF antisera. At
maximally neutralizing concentrations, IL-3 antiserum inhibited 66% of the
megakaryocyte colony growth stimulated by PHA-LCM. Residual megakaryocyte
colony growth was eliminated by the addition of a 1/500 dilution of
anti-GM-CSF.(ABSTRACT TRUNCATED AT 250 WORDS)
Volume 76,
Issue 2,
pp. 290-297,
07/15/1990
Copyright © 1990 by The American Society of Hematology
