AML T cells are able to conjugate effectively with autologous AML blasts but show impaired immune synapse formation and recruitment of T-cell signaling molecules. T cells from AML patients or age-matched healthy donors (healthy) were allowed to conjugate with autologous (auto) AML or healthy autologous B cells, respectively, ± sAg acting as APCs (CMAC dyed, blue). Conjugates were then fixed, stained, and scored by visual counting using confocal microscopy. (A) Percentage of T-cell–forming conjugates. (B) Percentage of T-cell conjugates resulting in F-actin (rhodamine phalloidin, red) polarization. (C) Percentage of T-cell conjugates resulting in phosphotyrosine polarization (P-Tyr, green) at the T-cell immune synapse. Data are the mean ± SD from 10 independent experiments with 50 conjugates analyzed per experiment. Arrows indicate protein localization at the T-cell–APC synapse site. Original magnification × 63. Statistical differences between experimental groups were evaluated by 2-tailed Student t test. P < .05 was considered statistically significant.