Nonmalignant T cells stimulate growth of malignant T cells in the presence of SEA. (A) Malignant T cells (SeAx) were grown with or without irradiated (to be devoid of the proliferative capacity) nonmalignant T cells (P1675) and/or SEA (100 ng/mL) in microtiter plates. Twelve hours prior to harvest, ³H-thymidine (1 μCi [0.037 MBq]/well) was added, the cells were harvested onto glass fiber filters, and ³H-thymidine incorporation was measured. The proliferation was expressed as mean counts per minute of triplicate cultures. The data are representative of 3 independent experiments. (B) Malignant T cells (MyLa 2039) and nonmalignant T cells were grown with or without irradiated nonmalignant T cells (MyLa 2355) and/or SEA (100 ng/mL) in microtiter plates. The data are representative of 4 independent experiments. (C) Malignant T cells (MyLa 1929) were grown with or without irradiated nonmalignant T cells (MyLa 1850) and/or SEA (100 ng/mL) in microtiter plates. Error bars represent SD.