Clearance kinetics of soluble pre-formed immune complexes containing IgM antibodies in normal and decomplemented rabbits.
The clearance kinetics of homologous soluble pre-formed 125I-BSA/IgM anti-BSA immune complexes (IgM . IC) injected into the blood was studied in the rabbit. IgM . IC close to equivalence were cleared with a greater velocity than those in x 5 or x 10 antigen excess. Clearance of BSA specifically bound to antibody, was measured by the Farr assay and found to exhibit an exponential mode of elimination suggesting a selective removal of large over small lattice complexes or free antigen. The role of C3 in the clearance of IgM . IC was examined by treating rabbits with cobra venom factor (CVF). While more variation was noted in CVF-treated rabbits, no statistically significant differences could be detected between C3-depleted and control animals. It is, therefore, concluded that soluble preformed IgM . IC are cleared from the rabbit circulation by a C3b-independent mechanism. This finding for soluble IC is clearly different from the clearance of IgM-coated red cells from the circulation, which has previously shown to be highly C3b-dependent.
D000818:Animals; D000936:Antigen-Antibody Complex / Q000378:metabolism*; D003176:Complement C3 / Q000276:immunology*; D004546:Elapid Venoms / Q000494:pharmacology; D006207:Half-Life; D007075:Immunoglobulin M / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D011817:Rabbits; D012710:Serum Albumin, Bovine / Q000276:immunology
D000936:Antigen-Antibody Complex; D003176:Complement C3; D004546:Elapid Venoms; D007075:Immunoglobulin M; D012710:Serum Albumin, Bovine