PTCL-NOS tissues harbor microenvironmental immune cells. (A) Representative images of FFPE sections costained with fluorochrome-conjugated anti-CD20 (red) and -CD3 (green) antibodies. Immunofluorescence; original magnification ×20. CD20⁺ B cells were evident in the B-cell-signature–rich case (right) but not in a case lacking that signature (left). (B) Numbers of CD20⁺ cells and CD3⁺ cells were counted across sections using scanning software (see “Methods”). Frequencies of CD20⁺ cells relative to CD3⁺ cells are shown. **P < .01 (Wilcoxon rank-sum test). (C) Tumor sections were stained with anti-CD1A (orange), a DC marker, and anti-CD3 (green). Representative DC signature–rich (right) and –poor (left) cases are shown. Immunofluorescence; original magnification ×20. (D) Box-and-whisker plots represent Langerin (left) and IL-15 (right) mRNA levels in cases with or without the DC signature. *P < .05, **P < .01 (Wilcoxon rank-sum test). (E) IF was performed using antibodies against Langerin (cyan), a Langerhans cell marker, and CD3 (green), a T-cell marker. Representative images are shown. Immunofluorescence; original magnification ×20. Langerin expression was evident only in DC signature–rich cases (right). (F) Box-and-whisker plots represent frequencies of DCs as described in panel B. **P < .01 (Wilcoxon rank-sum test). (G) Bar graph shows Langerin mRNA levels in samples obtained from indicated biopsy sites. (H) IF was performed using antibodies against CD163 (pink), a macrophage marker, and CD3 (green). Representative images are shown. Immunofluorescence; original magnification ×20. (I) Frequencies of CD163⁺ macrophages relative to CD3⁺ cells are shown. **P < .01 (Wilcoxon rank-sum test).