CD8A and Menkes disease: Our data showed that the expression of IL4I1 was significantly increased in the susceptible line 72 birds at 10 dpi, while it remained unchanged in the resistant line 63 birds at the same time point, which indicated that genes like IL4I1 may contribute to immunosuppression and facilitate tumorigenesis through inhibiting the CD8+ antitumor T-cell response in MD susceptible chickens.