cHL exhibits MHC-II expression accompanied by CD4⁺T-cell infiltration. (A) Representative staining pictures for MHC-I and MHC-II. IHC was conducted on FFPE sections (3 µm thick) from 85 patients with cHL. (B-D) CD4⁺ and CD8⁺ T-cell infiltration according to the expression of MHC-I and MHC-II. IHC was conducted as described in panel A. Five fields (0.0625 mm²) containing HRS cells were randomly selected and counted for each slide. The average of the 5 area counts for each patient was used for statistical analysis. Representative immunohistochemically stained images (B) and summaries of the counts of CD4⁺ T cells and CD8⁺ T cells (C) are shown. (D) Summaries of cell counts according to the expression of MHC-I and -II are shown. *P < .05; **P < .01. N.S., not significant.