Complement-dependent killing of human hematopoietic progenitor cells with
noncomplement-fixing monoclonal antibodies in an antiglobulin assay
JH Fitchen, C Russo and S Ferrone
A complement (C)-dependent antiglobulin assay was utilized to determine the
reactivity of non-C-fixing monoclonal antibodies (MoAb) with human
granulocyte-macrophage progenitor cells (CFU-GM). The variables of the
assay were analyzed with non-C-fixing MoAb against Ia antigens, including
CR11-462, which recognizes the same (or spatially close) determinant
identified by the C-fixing anti-Ia MoAb Q5/13. The sensitivity of the
antiglobulin assay was influenced by dilutions of anti-mouse Ig
xenoantiserum and of rabbit C. Five non-C-fixing MoAb to Ia antigens, seven
non-C-fixing MoAb to HLA-A,B antigens, and one non-C- fixing MoAb to beta
2-microglobulin induced marked inhibition of human CFU-GM in the
antiglobulin assay. The activity of non-C-fixing MoAb in the antiglobulin
assay was comparable to that of C-fixing anti-Ia and anti-HLA-A,B MoAb in
the standard cytotoxicity assay. In addition, the cytotoxic effect of
dilute C-fixing anti-Ia MoAb was enhanced when the antiglobulin technique
was employed. The results of this study indicate that the antiglobulin
assay is a rapid and simple technique for the characterization of antigens
on human hematopoietic progenitors. Our data also indicate that Ia antigens
are expressed on most CFU-GM and that the conflicting results in the
literature (that is, those suggesting that Ia antigens are expressed on a
smaller proportion of CFU-GM) may reflect differences in the cytolytic
activity of the MoAb and rabbit C used.
Volume 63,
Issue 4,
pp. 873-877,
04/01/1984
Copyright © 1984 by The American Society of Hematology
