Deposition of immune complexes containing cationized antibodies in myocardial small blood vessels of mice.

Small myocardial blood vessels constitute a site for preferential deposition of preformed cationic immune complexes. This preferential deposition was demonstrated with a limited dose (100 micrograms) of cationized rabbit antibodies to human serum albumin, injected into C57B1/6J mice either alone or in the form of preformed immune complexes. Heart, kidney, liver, intestine, and skeletal muscle were examined for immune deposits by immunofluorescence microscopy. Highly cationized antibodies injected alone showed deposition in glomeruli and in the liver along the sinusoids but not in other tissues. Immune complexes containing native rabbit antibodies deposited only in liver in a Kupffer cell pattern. Moderate and highly cationized antibodies in immune complexes deposited in myocardial small blood vessels, liver, and glomeruli, but not in intestine or skeletal muscle. These complexes deposited via electrostatic interactions since unrelated polycationic molecules, protamine sulfate or cationized rabbit serum albumin, injected 1 min prior to cationic antibodies in immune complexes blocked deposition in myocardial small vessels, glomeruli, and liver. Administration of protamine or cationized rabbit serum albumin 1 min after deposition of cationized immune complexes resulted in displacement of the immune deposits in heart, kidney, and liver, but not when the injection was given 1 hr later. The presented data indicate that with passage of time the immune deposits rearrange and forces other than charge-charge interactions retain them in myocardial vessels.