The pattern of HLA-DR and HLA-DQ antigen expression on clonable
subpopulations of human myeloid progenitor cells
RL Sparrow and N Williams
Three subpopulations of human myeloid progenitor cells (CFU-GM) can be
distinguished by differences in their kinetics of development; the liquid
phase pre-CFU-GM, the day 14 CFU-GM, and the day 7 CFU-GM. The relative
cell membrane densities of the HLA-DR and HLA-DQ antigens expressed by the
three subpopulations was investigated by comparing the amount of antibody
required to deplete bone marrow cell preparations of each cell type. Three
separate approaches were used--complement (C') cytotoxicity,
antiglobulin/C'-cytotoxicity and immune rosette depletion. Similar results
were obtained for all three procedures, although the latter two gave a
tenfold greater sensitivity over the standard C'-cytotoxicity method. At
saturating anti-HLA-DR antibody concentrations, 85% to 95% of cells within
the three myeloid subpopulations were found to express HLA-DR antigens.
However, the relative amount of HLA-DR expressed by these subpopulations
increased from the pre-CFU-GM to the day 7 CFU-GM. The expression of HLA-DQ
antigens was considerably lower and could only be detected by using the
more sensitive procedures. Only 50% of day 7 and 14 CFU-GM progenitor cells
expressed detectable HLA-DQ antigens, whereas a greater proportion (80%) of
the pre-CFU-GM were HLA-DQ positive. The pattern of HLA-DQ expression on
these clonable precursors was quite distinct and opposite to the cell
membrane density of the HLA-DR antigens. Because these three progenitor
cell populations are thought to be linked in differentiation sequence,
these results provide indirect support for the hypothesis that HLA class II
antigens are implicated in regulatory mechanisms during normal myeloid cell
differentiation.
Volume 67,
Issue 2,
pp. 379-384,
02/01/1986
Copyright © 1986 by The American Society of Hematology
