The specific in vitro antibody-mediated retention of bovine serum albumin by porcine hyaline articular cartilage.

Porcine hyaline articular cartilage (HAC) has been used to investigate the interaction of bovine serum albumin (BSA) and anti-BSA with articular collagenous tissues in vitro. There was a marked retention of 125I-labelled BSA by plugs of HAC (a) exposed to rabbit anti-BSA for 1-2 h at 37 degrees C prior to a similar incubation with the antigen, or (b) exposed to the antigen and then to antibody. The specifically retained radiolabelled BSA was localized in or at the articular surface of the plugs. In the absence of specific antibody a relatively small amount of the antigen was retained. Exposure of HAC to multiple cycles of antibody and antigen treatment resulted in an increased retention of the 125I-BSA. There was a concomitant increase in the retention of the anti-BSA and the capacity of the treated plugs to fix complement. The forces that maintained the labelled antigen in the tissue were not readily reversed by excess unlabelled BSA. Pre-formed, soluble BSA/anti-BSA complexes did not appear to penetrate the tissue unless the HAC was first exposed to anti-BSA. The results suggest that the antibody-mediated, surface oriented retention of 125I-BSA results from the formation of immune complexes in the tissue.