Furthermore, macrophages found during infection of mice with T. crassiceps are characterized by high expression of IL-4, programmed death ligand 1 (PD-L1), and programmed death ligand 2 (PD-L2), and inducible nitric oxide synthase (iNOS) but low levels of IL-12 [62, 63], rendering those macrophages as potent suppressors of lymphocyte proliferation, adhesion molecules, and chemokine expression. Here, NOS2 is linked to infection.