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G Kannourakis, GR Johnson, CG Begley, JA Werkmeister and GF Burns
Cancer Research Unit, Walter and Eliza Hall Institute, Victoria, Australia.
The enhancement of in vitro human hematopoiesis by the addition of a
noncytotoxic monoclonal antibody, 9.1C3, is described. Enhancement of all
aspects of in vitro hematopoiesis was observed on addition of 9.1C3
antibody to cultures of mononuclear cells from normal bone marrow, cord
blood, and peripheral blood from beta-thalassemia major patients. In
cultures with no exogenous colony-stimulating factor (CSF), the addition of
9.1C3 resulted in a two- to eightfold increase in nonerythroid colony
formation. Similarly, for cultures maximally stimulated with CSF, the
addition of 9.1C3 antibody resulted in a one- to fourfold increase in
colony formation. These effects were abrogated by the removal of either
adherent, Leu-M3+ or Leu-7+ cells. Colony- forming cells were shown to be
present among the 9.1C3-negative cells when mononuclear cells were sorted
by flow cytometry. Media conditioned in the presence of 9.1C3 and
mononuclear cells were able to enhance colony formation in vitro for normal
nonadherent bone marrow cells beyond that achieved with supramaximal
amounts of human placental- conditioned medium and erythropoietin. The data
suggest that natural killer cells interact with monocytes to exert a
negative regulatory control on in vitro granulopoiesis and erythropoiesis.
Consequently, the number of progenitor and multipotential cells in cultures
of unfractionated cell populations may be greatly underestimated.
This article has been cited by other articles:
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| Copyright © 1988 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
