Direct effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on functional properties of human T lymphocytes

Abstract

Background. We investigated direct effects of granulocyte-macrophage colony-stimulating factor (GM-CSF) on the functionality of T-lymphocyte subsets. Methods. CD3⁺ T cells were isolated from the blood of healthy donors by positive magnetic separation. The isolated T cells were activated with particles conjugated with antibodies (Abs) to human CD3, CD28, and CD2 molecules. The membrane expression of CD3, CD4, СD45RA, СD197, CD25, and CD38 was evaluated by flow cytofluorometry. Contents of interferon-γ (IFN- γ), interleukin-2 (IL-2), IL-4, and IL-10 in culture supernatants were determined by the enzyme immunoassay. Results. GM-CSF at 0.01-10.0 ng/ml had no significant effect on the content of CD25⁺ cells among activated T lymphocytes. At the same time, GM-CSF at 0.1-1.0 ng/ml was able to noticeably increase the content of CD38⁺ cells among both naive CD45RA⁺/CD197⁺ T cells and central memory CD45RA^–/CD197⁺ T cells without affecting the СD38 expression on effector CD45RA^–/CD197^– and terminally differentiated CD45RA⁺/ CD197^– effector T cells. At a relatively low concentration (0.01 ng/ml), GM-CSF significantly decreased T-cell production of INF-γ whereas at a high concentration (10.0 ng/ml), GM-CSF detectably enhanced the secretion of IL-2 and IL-4 while lowering IL-10 production. Conclusion. The findings suggest that GM-CSF is capable of supporting the activation of relatively low-differentiated T cells without significantly affecting the activation of highly differentiated T cells.