Activating FcγRs-bearing macrophages were major contributors to inhibition of axon regeneration.

<p>Sciatic nerves showing regeneration of MF in <i>op/op</i> mice treated with sham or GD1a/GT1b-2b mAb (A). Morphometry data showing that number of regenerating MF in WT mice and <i>op/op</i> mice treated with sham Ab or GD1a/GT1b-2b at sciatic (B) and tibial (C) nerve levels. *<i>p</i> < 0.01 (Student’s <i>t</i>-test). N = 12 per group. Serology showing the levels of circulating GD1a/GT1b-2b mAb in <i>op/op</i> mice and WT animals (D). Micrographs (E) and morphometry (F) showing that mutant graft transplanted in mutant host had the most regeneration, wild type graft transplanted in mutant host had some regenerating fibers, and wild type graft or mutant graft transplanted in wild type hosts had virtually no regenerating fibers. *p < 0.05; **p < 0.001 (Two-way ANOVA, Bonferroni’s post-hoc test). N = 6 per group. Error bars, s.e.m. Scale bar, 10 µm. WG = wild type grafts, WH = wild type hosts, MG = mutant (<i>Fcer1g-null</i>) grafts, and MH = mutant (<i>Fcer1g-null</i>) hosts. NS = not significant; MF = myelinated nerve fibers.