Directs effects of granulocyte-macrophage colony stimulating factor (GM-CSF) on adaptive immunogenesis.

Background : We studied direct effects of human granulocyte-macrophage colony stimulating factor (GM-CSF) on phenotypical characteristics and cytokine-production of non-activated and activated human monocytes/macrophages (Mc/Mphs) and T cells. Methods : Purified Mc/Mphs were activated by bacterial lipopolysaccharide (LPS, 1 μg/ml) for 24 h, while T cells were activated by particles conjugated and antibodies (Abs) against human CD2, CD3, and CD28 for 48 h. Results : GM-CSF treatment (0.01-10 ng/ml) was shown to reduce percentages of CD197 (CCR7)-positive cells in non-activated Mph cultures, without affecting significantly CD14 ⁺ (LPS co-receptor), CD16 ⁺ (FcγRIII, low-affinity Fc-receptor), CD119 ⁺ (interferon-gamma receptor 1), and CD124 ⁺ (IL4 receptor α-subunit) cells. In addition, GM-CSF reduced relative numbers of CD197 ⁺ cells, as well as CD14 ⁺ , CD16 ⁺ , and CD119 ⁺ cells in activated Mph cultures without affecting CD124 ⁺ cell distribution. GM-CSF at the highest dose of 10 ng/ml enhanced TNF-α and IL-6 (but not IL-1β and IL-10) production in activated Mc/Mphs. In activated T cell cultures, GM-CSF at 0.1-1.0 ng/ml augmented CD38 ⁺ cell numbers in naïve СD45RA ⁺ /СD197 ⁺ and central memory СD45RA ^- /СD197 ⁺ cell subsets, with no effect on effector СD45RA ^- /СD197 ^- and terminally differentiated effector СD45RA ⁺ /СD197 ^- cells. GM-CSF at a low dose (0.01 ng/ml) down-regulated INF-γ production, while at a high dosage (10.0 ng/ml) up-regulated IL-2 and IL-4 production. Conclusion : In general, the results suggest that GM-CSF is able to facilitate the implication of both Mph and T cells in the adaptive immunogenesis.