Anti-pig IgM antibody levels in baboons with or without the administration of anti CD154mAb or CTLA4-Ig. (The shaded area indicates the period of time when immunosuppressive therapy was being administered to B309 and B209.) (Reprinted with permission from Dons et al. 2012.) In naïve, non-immunosuppressed infant baboons (n=6), after 3 months of age, anti-pig IgM antibody levels rose significantly and continued to increase at 6, 9, and 12 months of age. In contrast, anti-pig IgM antibody level in an anti-CD154mAb-treated infant baboon (B309) remained very low while immunosuppressive therapy was being administered, but rose after discontinuation of the anti-CD154 mAb. In a CTLA4-Ig-treated infant baboon (B209), anti-pig IgM antibody began to increase before discontinuation of CTLA4-Ig.