mRNA in situ hybridization for IFNG and immunohistochemistry (IHC) of CD4 and CD8. Representative microphotographs and quantitative analyses of mRNA in situ hybridization for IFNG and IHC for CD4 and CD8 showing the increase in the prevalence of CD8⁺ cytotoxic lymphocytes expressing IFNG in BL case. Original magnification, ×200 and ×400.