Spontaneous peripheral lymphocyte activation in p66Shc^−/− mice. Flow cytometric analysis of untreated lymphocytes from spleen and lymph nodes from 12-month-old control (+/+, gray) or p66Shc^−/− (−/−, black) mice stained with the indicated cells surface markers. (A, top) Representative fluorescence-activated cell sorting (FACS) profiles of CD3/CD22 and CD4/CD8 labeling of lymphocytes from spleen (left) and lymph nodes (right). The percentage of cells that falls into the indicated quadrants is indicated. (Bottom) Histograms displaying the mean values (± SD) are shown below. For each sample, fluorescence was analyzed on gated cells with forward and side light scatter properties of lymphocytes (n ≥ 6). (B,C) Representative FACS profiles of CD3/CD69, CD3/CD25, and CD22/CD69 labeling of lymphocytes from spleen (B) and lymph nodes (C). Histograms show the percentage (mean values ± SD) of CD69⁺ or CD25⁺ T cells and of CD69⁺ B cells (n ≥ 6; *P < .05; **P < .01; ***P < .001).