Immunoperoxidase, immunofluorescence stain, and Western blot were performed as previously described.17 (link),18 (link) The following antibodies were used: polyclonal anti-C4d (American Research Products); polyclonal anti-CD3 (Abcam); anti-CD68 (clone ED1, Biorad); anti-PAX5 (clone A-11, Santa Cruz); and anti-GAPDH (clone 6C5, Abcam).