PTPRC and infection: To determine whether Lm infection results in upregulation of donor MHCII on endothelial cells of tolerant grafts, tolerant heart recipients were infected with Lm at day 30+ after transplantation with CoB treatment and CD45–CD31+ donor-derived endothelial cells from the graft were evaluated 4 to 8 days after infection for expression of I-Ad/I-Ed (gating shown in Figure 5A).