PDCD1LG2 and infection: However, the expression of PD-L2 was stimulated upon infection with C. hepatica and increased gradually to the highest point at the termination of the infection (12th week post-infection; Figure 2e–g), further suggesting that M2 macrophages and the PD-1/PL-2 pathway are mainly involved in the regulation and modulation of immune responses to the infection of C. hepatica, especially to the eggs of the worm in the late stage of infection.