Background A mouse model of destructive antibody-mediated polyarthritis (AMPA) induced by a combination of four or five different monoclonal antibodies (mAbs) specific for type II collagen (CII) was previously established. However, it has not been well defined whether an anti-CII mAb is able to induce AMPA.
Objectives The present study aimed to produce an anti-CII mAb that induced destructive AMPA in mice.
Methods To establish anti-CII mAb-producing hybridomas, DBA mice were repeatedly sensitized with chicken CII plus CFA and then CII-sensitized spleen cells were fused with myeloma cells before cloning fused-cells producing mAbs against mouse CII. To induce arthritis, DBA mice were i.p. injected with various doses of each produced anti-CII mAb (day 0), followed by i.p. administration of LPS on day 3. To evaluate the severity of the arthritis, lesions of the four paws were each graded from 0 to 3 according to the increasing extent of erythema and edema of the periarticular tissue. Histological analysis of inflamed joints and measurement of C3 in serum were also performed.
Results A number of hybidomas producing different isotypes of anti-CII mAbs including IgG1, IgG2a, IgG2b, IgG3, and IgM were established. I.p. injection of various doses of each anti-CII mAb into DBA mice revealed that only two mAbs (C2B-9 and C2B-14) induced arthritis by the injection without a combination of the mAbs. The incidence of AMPA was 100% in the 5 mice injected with either C2B-9 or C2B-14. However, C2B- 9 induced only mild arthritis while C2B-14 induced moderate joint inflammation, although injection of both C2B-9 and C2B-14 induced severe arthritis. The isotype of C2B-9 and C2B-14 was IgG2b. Histologically, marked hyperplasia of the synovium as well as destruction of cartilage and bone was observed in mice injected with C2B-14 but not C2B-9. Significant decreases in C3 in serum were also observed in C2B-14- but not in C2B-9 -injected animals.
Conclusions We successfully produced an anti-CII IgG2b mAb, C2B-14, that induced destructive AMPA. The destructive AMPA by C2B-14 was associated with low levels of C3 in serum, suggesting a role of complement activation in C2B-14-induced AMPA.
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Acknowledgement This work was supported by a Grant-in-Aid for Scientific Research (C) from the Japan Sciety for the Promotion of Science.
Disclosure of Interest None declared