Phenotype of CD27-defined T-helper cell subsets. Seven-colour FCM including a live/death discrimination dye was used to study CD45RC and SLA-DR expression on CD8α/CD27-defined T helper cells. (A) CD3+CD4+ T helper cells were gated (upper left contour plot) and analysed for CD27 (x-axis) versus CD8α, CD45RC and SLA-DR (y-axes) expression (middle column). CD8α/CD27-defined cell populations (CD8α-CD27+, blue gate; CD8α+CD27+, green gate; CD8α+CD27-, red gate) were further subgated for CD45RC (x-axes) versus SLA-DR (y-axes) expression as depicted by coloured contour plots (right column). (B) CD8α and CD27 expression of CD3+CD4+ T helper cells as well as CD45RC and SLA-DR expression of CD8α/CD27-defined T-helper cell subpopulations (gating strategy as in A) in blood (PBMCs), spleen, mediastinal (Med. LN), bronchial (Bron. LN) and mesenteric lymph nodes (Mes. LN), tonsil, and liver (columns from left to right; numbers indicate percentage of cells in respective gates). (A + B) See main text for description of arrow heads and numbers. Data of one representative animal out of five is shown. At least 1× 105 lymphocytes per sample were acquired.