title: Enhancing effect of autologous human erythrocytes on generation of C3 cleavage products beyond iC3b.
abstract: The in vitro formation of C3d and C3c in fresh normal human serum (NHS) after addition of five different activators of the complement (C) system was studied. Following C-activation in NHS (n = 53) by Sephadex G-200 beads, the conversion of C3 was found to proceed to iC3b with a variable but restricted generation of C3d. Similar results were obtained by use of heat-aggregated IgG, Escherichia coli, zymosan, and cobra venom factor. However, comparing the C3d concentration following activation in the presence and absence of autologous red blood cells (RBC) at 37 degrees C the generated C3d was found to be 2- to 3-fold higher in the presence of RBC after 30, 60, and 210 min. Preincubation of RBC with polyclonal anti-CR1 antibodies resulted in a dose-dependent reduction of the amount of C3d generated. C-activation induced by Sephadex G-200 beads, in the absence of RBC, generated iC3b without a significant production of C3d. After removal of the activator beads, addition of RBC resulted in a decrease of iC3b and a clear increase in the C3c and C3d concentration within 3 h. Western blotting analysis of the C3d produced in the presence of RBC showed that the molecular weight (36 kilodaltons) was similar to that of C3d formed in vivo.
mesh_terms: D015153:Blotting, Western; D003167:Complement Activation; D003176:Complement C3 / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004912:Erythrocytes / Q000502:physiology*; D005340:Fibrinogen / Q000032:analysis; D006801:Humans; D007122:Immunoelectrophoresis; D007163:Immunosorbent Techniques
chemical_list: D003176:Complement C3; D005340:Fibrinogen