Interleukin-8 favors pro-inflammatory activity of human monocytes/macrophages.

Interleukin-8 (IL-8, CXCL8) belongs to major chemokines to stimulate migration of neutrophils and monocytes/macrophages (Mc/Mphs) into the inflammation sites. We studied the direct effects of IL-8 on the functionality of human Mc/Mphs in vitro. CD14-positive cells were isolated from human peripheral blood mononuclear cells (PBMCs) by positive magnetic separation and were further cultured with or without lipopolysaccharide (LPS, 1.0 µg/ml) for 24 h. We showed that upon LPS activation of Mc/Mphs, IL-8 reduced markedly both the percentages and median fluorescence intensity (MFI) of CD16 (FcγRIII)-positive cells among CD14high cells, as well as in cells that reduced the expression of СD14 during their culturing. IL-8 was also found to be capable of reducing the expression of СD124 (IL-4 receptor subunit alpha, IL-4RA), with concomitant enhancement of the expression of both CD119 (interferon-gamma receptor 1) and CD197 (CCR7) in Mph cells. In addition, IL-8 up-regulated production of IL-6 and IL-1ß [but not tumor necrosis factor-α (TNF-α) and IL-10] by activated Mc/Mphs. Our results suggest the ability for IL-8 to directly favor pro-inflammatory M1-type Mph activity.

Direct anti-inflammatory effects of granulocyte colony-stimulating factor (G-CSF) on activation and functional properties of human T cell subpopulations in vitro.

We investigated the direct effects of human granulocyte colony-stimulating factor (G-CSF) on functionality of human T-cell subsets. CD3+ T-lymphocytes were isolated from blood of healthy donors by positive magnetic separation. T cell activation with particles conjugated with antibodies (Abs) to human CD3, CD28 and CD2 molecules increased the proportion of cells expressing G-CSF receptor (G-CSFR, CD114) in all T cell subpopulations studied (CD45RA+/CD197+ naive T cells, CD45RA-/CD197+ central memory T cells, CD45RA-/CD197- effector memory T cells and CD45RA+/CD197- terminally differentiated effector T cells). Upon T-cell activation in vitro, G-CSF (10.0 ng/ml) significantly and specifically enhanced the proportion of CD114+ T cells in central memory CD4+ T cell compartment. A dilution series of G-CSF (range, 0.1-10.0 ng/ml) was tested, with no effect on the expression of CD25 (interleukin-2 receptor α-chain) on activated T cells. Meanwhile, G-CSF treatment enhanced the proportion of CD38+ T cells in CD4+ naïve T cell, effector memory T cell and terminally differentiated effector T cell subsets, as well as in CD4- central memory T cells and terminally differentiated effector T cells. G-CSF did not affect IL-2 production by T cells; relatively low concentrations of G-CSF down-regulated INF-γ production, while high concentrations of this cytokine up-regulated IL-4 production in activated T cells. The data obtained suggests that G-CSF could play a significant role both in preventing the development of excessive and potentially damaging inflammatory reactivity, and in constraining the expansion of potentially cytodestructive T cells.

Direct effects of interleukin-8 on growth and functional activity of T lymphocytes.

CD3+ T-lymphocytes were isolated from the normal donors by positive magnetic separation. Activation of the T cells with particles conjugated with antibodies to CD3, СD28 and СD2 molecules led to a marked increase in T-cell production of interleukine-8 (IL-8). We present evidence that IL-8 receptor α-chain (CXCR1, CD181) is expressed on the cell surface of 13.3% T cells. Activation of T-lymphocytes resulted in significant enhancement of CD181+ cells both in naive CD4+ T cell and terminally differentiated effector CD4+ T cell compartments with concomitant reduction of CD181+ cells in effector memory CD4+ T cell subset. The level of T cell activation was assessed judging from the surface expression of CD25 (IL-2 receptor α-chain). We demonstrate that IL-8 treatment (0.01-10.0ng/ml concentration range) reduced the activation status of both CD4- and CD4+ effector memory T cells, as well as terminally differentiated effector T cells, without significantly affecting the activation of naive T cells or central memory T cells. In addition, IL-8 up-regulated IL-2 and down-regulated IL-10 production by activated T cells, with no effect on interferon-gamma (IFN-γ) and IL-4 production. Data obtained suggests the importance of IL-8 in the direct regulation of adaptive T cell reactivity.