Fig. 1

Preventive effect of anti-mouse CD11b monoclonal antibody (5C6) treatment. a Comparisons of the cumulative incidence of arthritis and the age-associated changes in arthritis score (mean and SE) among untreated (n = 15), normal rat IgG-treated (n = 15), 5C6-treated FcγRIIB-deficient mouse strain (KO1) (n = 15), and B6 mice (n = 10). The incidence was significantly lower in 5C6-treated mice, compared with those in untreated and normal rat IgG-treated mice after 7 months of age (Kaplan-Meier method ***P < 0.001), and the arthritis score was significantly suppressed in 5C6-treated mice, compared with those in untreated and normal rat IgG-treated mice after 8 months of age (analysis of variance (ANOVA) *P < 0.05, **P < 0.01). b Comparisons of the width of the ankle joints at the tarsal bones (mean and SE) of at least 6 mice at 10 months of age among untreated, normal rat IgG-treated, 5C6-treated KO1, and B6 mice. Statistical significance is shown (ANOVA ***P < 0.001). c Representative macroscopic and histopathological findings in the hind paws in untreated, normal rat IgG-treated, and 5C6-treated KO1 mice at 10 months of age. Untreated and normal rat IgG-treated KO1 mice had marked synovitis with inflammatory cell infiltration, pannus formation (Pn), tartrate-resistant acid phosphatase (TRAP)-positive osteoclast generation (arrowhead), and the destruction of cartilage and bone. The 5C6-treated KO1 mice only had mild synovial lining cell proliferation (triangle) and a few small TRAP-positive osteoclasts in bone marrow (arrowhead). Representative results obtained from six female mice in each group. Hematoxylin/eosin (HE) and TRAP staining. Bars = 50 μm