Both LTα-expressing HRS cells and enhanced hyaluronan expression are detected in cHL lymph nodes. (A) Expression of LTα could be detected in HRS cells (red arrows) and in the stroma of cHL lymph node sections by IHC. The overall LTα staining intensity was categorized as (B) weak/negligible, (C) moderate, and (D) strong as indicated. (E) Labeling by HABP shows positive staining localized to the germinal centers of B-cell follicles and vascular structures in reactive lymph nodes. (F) Strong subendothelial positivity and punctuate luminal staining are seen in the HEV. (G) Intense HABP labeling is seen in the stroma with weaker intensity detected in the nodules (n) in cHL tissue. (H) Treatment of the tissue section with hyaluronidase completely abrogated HABP staining. (I) cHL section incubated with purified mouse IgG as primary Ab serves as the negative control. (J-K) Double-staining with anti-CD31 mAb and HABP confirms the expression of hyaluronan on endothelial cells in cHL section. Images shown are representative cases from 32 cHL cases for A-D; a representative sample from 10 reactive lymph nodes screened for E-F; a representative case from 10 cHL cases for G-I; and a representative of 10 cHL cases that were doubled-stained with anti-CD31 and HABP for J-K. IHC images were acquired using an Olympus BX43 microscope equipped with the Olympus DP72 camera at the following original magnifications: ×100 objective for A-D, F, and K; ×10 objective for E and G-I; and ×40 objective for J.