The demonstration of CD4 help-mediated CD8+ T cell expansion in portal tracts and PCV regions provides insight into the significance of periportal and PCV infiltrates long observed in a range of liver diseases with an immune-mediated component, including viral hepatitis, autoimmune hepatitis, liver transplant rejection and metabolic associated fatty liver disease (MAFLD)46–49. This evidence concerns the gene CD4 and viral hepatitis.