Interactions of immunoglobulins and chondrocytes

Our study relates to damage of articular cartilage by deposition of immune complexes. Addition of IgG to cultured chondrocytes affected their metabolism--boosting metalloprotease synthesis, generating superoxide anion (O2-), and reducing the synthesis of sulfated glycosaminoglycans (S-GAG). Heat aggregation of the IgG enhanced its effect on O2- and S-GAG. Some interleukin 1 beta (38 pg/ml) was detected by ELISA after exposure to heat aggregated IgG. There was no cytotoxic effect due to IgG alone, but addition of complement (5% bovine serum) caused significant loss of intracellular 51Cr, which was further increased by addition of heat aggregated IgG. Similar responses of chondrocytes in vivo might account for immune complex mediated damage of cartilage.