Report of Two Cases With an Immunopathological Review

Two cases of relapsing polychondritis are described. Immune reactions against cartilage are discussed, with reference to the protection of chondrocytes from immune reactions by matrix, and antibody‐ and cell‐mediated responses to cartilage matrix components. Cell‐mediated responses to proteoglycan are probably more important than antibodies in the pathogenesis of relapsing polychondritis, but are unlikely to initiate the disease process. Cartilage may be injured as an ‘innocent bystander’ in immune reactions, because of its affinity for immune complexes. This, and the cross‐reaction between cartilage antigens and streptococcai antigens, could be of importance in the pathogenesis of relapsing polychondritis.