Monoclonal antibodies to the 140,000 mol wt glycoprotein of B lymphocyte
membranes (CR2 receptor) initiates proliferation of B cells in vitro
BS Wilson, JL Platt and NE Kay
Several mouse monoclonal IgG antibodies (AB1, AB2, AB3, and AB5) were
developed that reacted with a 140,000 mol wt glycoprotein on the surface of
cultured RAJI B lymphoid cells. The antibodies reacted with purified normal
human peripheral blood B cells and CLL Ig+ B cells and showed specific
germinal center and mantle zone staining in tissue sections of secondary
lymphoid organs. Immunodepletion studies using 125I surface-labeled Raji
cell membrane antigens demonstrated that the antigen identified by AB5 is
the same 140,000 mol wt glycoprotein detected by anti-B2 that has recently
been shown to react with the C3d fragment or CR2 receptor. (Iida et al: J
Exp Med 158:1021, 1983). Addition of the AB series and anti-B2 monoclonal
antibodies to cultures of purified human peripheral blood B cells resulted
in the uptake of 3H- thymidine at two to six times background control
levels provided that irradiated autologous T cells were added to the
culture. Stimulation was not evoked by other monoclonal antibodies to B
cell surface molecules (ie, B1, BA-1, BA-2, and HLA-DR). Pepsin-generated
F(ab')2 fragments of anti-CR2 antibodies were essentially as effective as
the intact IgG molecule in stimulating B cells. Induction of B cell
proliferation by antibody binding to CR2 suggests that the C3d receptor may
have an integral role in regulation of humoral immune response.
Volume 66,
Issue 4,
pp. 824-829,
10/01/1985
Copyright © 1985 by The American Society of Hematology
