Immunophenotyping of TIL from a C-KS lesion (nodular type). Cells were recovered and cultured in the presence of TCM, as reported in Materials and Methods. Floating cells were phenotyped after 3 days of culture in TCM. (A) Nearly all of the cells (92%) are represented by lymphocytes, as assessed by the LeukoGATE system, which allows the discrimination between these cells, other mononuclear cells, and debris. (B) No CD19⁺ B cells were found in cultured lesions. Shown is a single immunofluorescence from a representative case. (C) Triple immunofluorescence from a representative case showing that the majority of the cells coexpress the α/β chain of the TCR as well as the CD4⁺ (24%), the CD8⁺(39%), or both CD4⁺CD8⁺ (13%) markers. Notably 24% of TCRα/β⁺ cells are CD4^-CD8^-. The figure represents the CD4 and CD8 staining on α/β positive gated cells. (D) Apoptotic figures are observed by morphologic analysis for orthogonal (y-axis) versus forward (x-axis) light scatter. A, apoptotic region; B, viable lymphocytes. {/CAPT;;;left;stack}