Figure 4.

GM-CSF boosts cytokine production by T helper cells. To examine the mechanism of ThGM cell help on Th1 and Th2 cells, supernatant from restimulated ThGM cells (ThGM sup) was added, with or without anti-GM-CSF (10 μg/ml), to differentiated Th1 or Th2 cells during their restimulation with anti-CD3, and supernatants collected after 36 h and assayed for IFN-γ and IL-4 (a). The same ThGM sup, PFA-fixed ThGM cells (ThGM(F)), or ThGM cells on transwells (ThGM(trans)), were co-cultured with differentiated Th1 or Th2 cells during anti-CD3 stimulation, and IFN-γ and IL-4 were assayed (b). CD8⁺ cells were cultured alone or with ThGM cells and supernatants assayed for TNF-α at the indicated times after restimulation (c). Th1, Th2, or ThGM cells were differentiated in the presence or absence of GM-CSF (5 ng/ml) and then restimulated and supernatants assayed for IFN-γ and IL-4 (d). All ELISA results are mean±S.E.M. of at least four different experiments, *P<0.05; **P<0.01