Direct effects of G-CSF on IFN-γ and IL-4 production by CD4⁺ T lymphocytes.

Monocytes and CD4⁺ cells from normal donors were purified to obtain preparations with more than 98% purity as determined by flow cytometry using CD4 and CD14 mAb. Monocytes and CD4⁺ cells were separately exposed to G-CSF for 24 hours, washed, and mixed together (ratio 1:1). The expression of IFN-γ and IL-4 was measured using an intracellular staining technique and flow cytometry. Bars represent the changes (mean ± SEM) in the percentage of cells expressing IFN-γ (gray) and IL-4 (black) over a control mixture of monocytes and monocytes not exposed to G-CSF (summary of 2 independent experiments).