Summary Antibodies to type II collagen (CII) cause articular damage in collagen-induced arthritis (CIA) in mice as judged by passive transfer to naive animals of mAb to CII. We tested the hypothesis that mAb degrade cartilage structure by reacting with functionally important regions of the collagen molecule by examining the effects of an arthritogenic mAb to CII, CII-C1, on cultured bovine chondrocytes at high density, at days 7 and 14. The effects were compared of CII-C1, an isotype-matched control mAb, or medium alone, on chondrocyte proliferation and viability, cell morphology, matrix structure by light and electron microscopy, and matrix synthesis by metabolic labelling with 3 H-proline for collagen or 35 SO 4 for proteoglycans. Chondrocytes in culture remained viable, proliferated, and produced an extracellular matrix in which CII was the major collagen. The addition of CII-C1, but not a control mAb, increased the synthesis of CII and proteoglycan, and caused disorganization of the extracellular matrix and thin collagen fibrils ultrastructurally. Moreover, using a cell-free assay, CII-C1 inhibited the normal selfassembly of collagen fibrils from CII in solution. The finding that the mAb to CII, CII-C1 has striking degradative effects in vitro on cartilage synthesis suggests that antibodies to collagen perpetuate the chronic phase of CIA and that, in mice at least, such antibodies are an important component of pathogenesis.

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Summary:In a cross-sectional study of 100 healthy elderly individuals, anticardiolipin antibodies (aCL) were measured using an ELISA technique. aCL were not detected in the majority ofsubjects (63%), and in the remaining 37% titres were within the laboratory reference range (mean + 5 standard deviations) previously determined for adults of all ages. In contrast, significant titres of IgM rheumatoid factor were found in 10%, antimitochondrial antibody in 13%, antinuclear factor in 5%, anti-smooth muscle antibody in 18%, antiparietal cell antibody in 10%, and antireticulin antibody in 1%. Antibodies to single or double-stranded DNA were not detected in any subject.We conclude that, although other auto-antibodies may be present in the healthy aging population in Britain, abnormally elevated levels of aCL antibody do not occur, and when present may be an indicator of autoimmune-mediated pathology.

A 66 kDa protein, denoted P66, not hitherto classified as an integral component of yeast mitochondrial ATPase, is often observed in preparations of this enzyme complex. A physical association exists between P66 and the assembled ATPase complex since both components are coimmunoprecipitated by anti-F,8 monoclonal antibody. Two recombinant clones expressing proteins immunologically similar to P66 were isolated from a yeast genomic library in Igtl 1 by screening with a polyclonal anti-holo-ATPase antibody. Based on restriction site mapping and partial nucleotide sequence analysis, both clones encompass the gene encoding the yeast heat shock protein hsp60. The identification of P66 with hsp60, taken together with its demonstrated association with the mitochondrial ATPase complex, is consistent with recent suggestions that hsp60 is involved in assembly of the ATP synthaae complex.