Metabolism and clearance of antibody-excess immune complexes in lactating mice.

The metabolism of antibody-excess immune complexes was compared in lactating and normal female BALB/c mice. The initial rate of clearance of the antigen, dinitrophenyl- (DNP) ovalbumin, when complexed with mouse anti-DNP antibody was considerably faster in lactating mice. The half-life was 4 min in lactating mice compared with 8 min in normal female mice. Tissue distribution studies revealed that by 2 hr the mammary gland had sequestered immune complexes in threefold to fourfold excess over the levels in the liver. These lactating mice were shown to transfer immune complexes to their milk, and small quantities of the complexes could be demonstrated in the circulation of the nursing neonates.