C57BL/6 mice and the following gene-targeted strains were obtained from Jackson Laboratory (Bar Harbor, ME): C57BL/6-TG(CAG-EGFP), IFNγR1-deficient (B6.129S7-Ifngr1tm1Agt/J), and a CD45 congenic mouse strain (B6.SJL-Ptprca Pepcb/BoyJ). CD45.1 × CD45.2 mice were generated by crossing C57BL/6 (CD45.2) mice with Pepcb/BoyJ (CD45.1) mice. The MIIG (Mϕ-insensitive to IFNγ) strain was previously described [25 (link)] and a gift of Dr. Michael Jordan. All mice were bred and housed in the Animal Research Facility at Albany Medical College under microisolator conditions.