The effect of complement-sufficient antiserum against pig erythrocytes on pig articular tissues in organ culture.

Pig cartilage devoid of marrow or synovium is virtually unaffected by rabbit complement-sufficient antiserum to pig erythrocytes (AS + C'), probably because normal cartilage matrix excludes immunoglobulins. When synovium or invading marrow is present, AS + C' causes depletion of the proteoglycan, with consequent entry of IgG into the cartilage, followed by the breakdown of collagen; the chondrocytes assume a fibroblastic form and their reaction with the antiserum is greatly reduced. If degradation of the matrix has not advanced too far, new matrix is regenerated when the explant is transferred to control medium. Experiments on the depletion of pure cartilage by exposure to retinol, indicate that articular cartilage produces enzymes capable of degrading protoglycan but not collagen. The work was done in collaboration with colleagues at the Strangeways Laboratory and in the Division of Immunology, Pathology Department, University of Cambridge.