PILAR, but not CD161, is expressed by a proportion of both CD4⁺ and CD8⁺ tumor-infiltrating T cells. (A) CD161 is expressed by individual cells in the ovarian carcinoma microenvironment. Data are representative of 20 immunostained specimens. Original magnification, ×100 (left); ×200 (right). Photomicrographs were taken with a Nikon Eclipse 801 (Nikon, Melville, NY) at 10× (left) or 20× (right) 0.30 plan Fluor objective. Images were acquired using Micropublisher v. 5.0 (QImaging, Surrey, BC) and processed using Image ProPlus v. 5.1.1 (Media Cybernetics, Bethesda, MD). (B) PILAR (polyclonal Ab) is expressed by tumor-associated CD4 and CD8 T cells, whereas CD161 is only found on CD4 T lymphocytes. Gated on viable cells. Numbers in quadrants indicate percentage of CD3⁺ T cells in that quadrant. (C) Expression of both PILAR and CD161 can be recovered on tumor-associated cytotoxic T cells ex vivo by CD3/CD28 (100 ng/mL each) stimulation. Dotted, tumor-derived unstimulated CD8⁺ T cells; thick, the same cells after stimulation with CD3/CD28 for 5 days. Gated on viable cells.