Expression of Ia antigens on myeloid progenitor cells in chronic myeloid
leukemia: direct analysis using partially purified colony- forming cells
SA Cannistra, JF Daley, P Larcom and JD Griffin
The regulation of Ia (HLA-DR) antigen expression on myeloid progenitor
cells may be closely related to the control of myelopoiesis in both normal
individuals and chronic myeloid leukemia (CML) patients. In an effort to
study directly the expression and behavior of Ia surface molecules on
myeloid progenitor cells, we used an immunologic purification technique to
enrich these cells approximately 100-fold from the peripheral blood of CML
patients. The majority of cells in this blast population expressed HLA-DR
antigens. Thirty percent to 40% of cells could form a granulocyte or
monocyte colony in agar, and these cells tended to express the highest
levels of HLA-DR. The number of HLA- DR molecules per cell increased about
twofold as the cells tranversed the cell cycle from G0/G1 to G2/M. This was
true for unstimulated cells or cells exposed to colony-stimulating factors.
Some of this increase was related to a corresponding increase in cell size
and is also seen with other cell surface antigens such as
beta-2-microglobulin. Ia antigen expression was not modified by culture
with colony-stimulating factors, fetal calf serum, or serum-free,
prostaglandin-free medium for periods of up to 24 hours. These results
demonstrate that Ia antigens are expressed on the myeloid progenitor cells
of CML, are increased in the S and G2/M phases of the cell cycle, and are
stable under most in vitro culture conditions for at least 24 hours of
culture.
Volume 65,
Issue 2,
pp. 414-422,
02/01/1985
Copyright © 1985 by The American Society of Hematology
