Effect of RBCs on the activation of human complement by heparin- protamine
complexes
KA Shastri, MJ Phillips, S Raza, GL Logue and PK Rustagi
Department of Medicine, State University of New York at Buffalo.
Complement activation on red cells by heparin-protamine complexes was
studied by using whole human serum. C3 bound to red cells was measured by
radiolabeled monoclonal antibody to C3, and fluid-phase C5a was determined
by radioimmunoassay. Heparin and protamine in clinically relevant
concentrations caused the binding of C3 to red cell membranes, and the
measurement of C3 binding provided a sensitive indicator of complement
activation produced by these complexes. Complement activation by these
reagents occurred at concentration ratios of protamine and heparin at which
protamine neutralized the anticoagulant effect of heparin.
Heparin-protamine complexes appeared to bind to red cells and produce
complement activation by the classic pathway. C5a generation with
heparin-protamine complexes in serum was greatly enhanced in the presence
of red cells and increased with increasing red cell concentration. This
enhancement of complement activation in the presence of red cells was also
seen as measured by depletion of available C3 hemolytic complement units in
the fluid phase. Thus red cells seem to play an important role in
activation of complement by heparin-protamine complexes.
Volume 71,
Issue 1,
pp. 36-40,
01/01/1988
Copyright © 1988 by The American Society of Hematology
