FIGURE 2 .

An age-related defect in LAT phosphorylation in naïve and memory CD4⁺ T cells isolated from the spleens of young and aged mice is reversed by vitamin E. Fixed splenocytes were surface stained for CD4 and CD44, stained intracellular antigens, and analyzed by flow cytometry. (A–C) The percentages of pY191-LAT positive cells within populations gated for (A) naïve T cells (CD44^lo, CD4⁺) or (B) memory T cells (CD44^hi, CD4⁺) are shown. (C) Control intracellular stains were performed with normal rabbit serum or without primary antibody. All panels are representative of 7 independent experiments. (D,E) The frequencies of pY191-LAT positive cells within the naïve (D) and memory (E) CD4⁺ T cell subpopulations were determined in 7 replicate experiments examining the effects of age, vitamin E supplementation, and stimulation. The mean percentages ± SEM are shown, n = 7. *Different from young, P < 0.05 (Student's paired t test); ^#different from vehicle control, P ≤ 0.05 (Student's paired t test).