Direct effects of interleukin-7 on the function of human T cells in vitro

CD3+ T lymphocytes were isolated by positive magnetic separation from the peripheral blood of healthy donors. In the absence of any additional activating stimuli, interleukin-7 (IL-7) was shown to augment the levels of T cells expressing CD25 activation marker both in CD4-positive and in CD4-negative effector memory (CD45RA(-)CD197(-)) T cell subsets, as well as in terminally differentiated (CD45RA(+)CD197(-)) T cells, without significantly affecting the activation status of naive (CD45RA(+)CD197(+)) and central memory (CD45RA(-)CD197(+)) T cells. In addition, IL-7 noticeably enhanced the production of IL-2, interferon-gamma (IFN-gamma), and IL-10, but not IL-4, in T cells. The direct effects of IL-7 on T cell activation induced in vitro by MACSiBead (TM) particles coated with CD2, CD3, and CD28 antibodies (Abs) were also investigated. Upon cell activation, IL-7 significantly augmented the levels of CD25+ T cells in naive (CD45RA+CD197+), central memory (CD45RA(-)CD197(+)), and effector memory (CD45RA(-)CD197(-)) T-cell compartments. In addition, IL-7 facilitated activation of CD4(-) (but not CD4(+)) terminally differentiated effector (CD45RA(+)CD197(-)) T cells. Finally, IL-7 was found to upregulate the production of IL-2, IFN-gamma, IL-4, and IL-10 by activated T cells. In conclusion, we speculate that IL-7 is capable of enhancing functional T cell activity without causing significant functional inbalance between various T cell subsets.