Skip to main content
. 2019 Aug 12;129(9):3754–3769. doi: 10.1172/JCI128010

Figure 3. IgG-IC elicits acute articular hypernociception in naive mice.

Figure 3

(A–E) Mice were injected intra-articularly (i.a.) with IgG-IC (1, 10, 100 μg/mL; 10 μL), monomeric IgG (100 μg/mL; 10 μL), or vehicle (PBS; 10 μL), and pain-like behaviors and joint diameter were evaluated over 1–24 hours. Injection of IgG-IC, but not monomeric IgG, reduced mechanical threshold in the ankle (A) and increased the frequency of paw withdrawal in response to application of 0.07 and 0.4 g force via a von Frey filament (B and C), but did not induce heat hyperalgesia (D) or visible joint swelling (E) in the ipsilateral paw, compared with vehicle. n = 8–10 mice per group; *P < 0.05 vs. PBS, #P < 0.05 vs. before injection; 2-way ANOVA for repeated measures followed by Bonferroni’s post hoc test. PWF, paw withdrawal frequency; PWL, paw withdrawal latency. (F) Representative sections of knee joints taken 1 hour after i.a. injection with either PBS, monomeric IgG, or IgG-IC and stained for Ly6C/G, CD68, CD3, or c-Kit. S, synovium. Scale bar: 200 μm. (G) Quantification showed no significant differences between treatment groups. n = 4–5 mice per group; P > 0.05; 1-way ANOVA followed by Tukey’s test. (H) Representative sections of knee joint taken 1 hour after i.a. injection with PBS, monomeric IgG, or IgG-IC, stained with H&E, and scored for synovitis. S, synovium. Scale bar: 100 μm. No significant difference in synovitis score was observed between treatments. n = 3–4 mice per group; P > 0.05; 1-way ANOVA followed by Tukey’s test.