Abstract: Objective To study the effect of interleukin 2 (IL-2) , which is within the clinical dose range, on the proliferation of human peripheral blood T cells, with special emphasis on the number and functional phenotype of γδT cells. Methods Human peripheral blood mononuclear cells (PBMCs) were isolated by density gradient centrifugation and cultured for 2 weeks at different IL-2 concentrations. Ratio and phenotype of different T cell subpopulations before and after in vitro expansion were explored by immunofluorescence staining. Cell number was estimated by trypan blue staining and cell counting. Results Within the four functional phenotypes of Vδ1 as well as Vδ2 γδT cells, CD27+ cells (including CD27+CD45RA+ and CD27+CD45RA- subsets) could express lymphoid tissue homing receptor CCR7, whereas CD27- cells (including CD27-CD45RA+ and CD27-CD45RA- subsets) had the peripheral tissue homing potential. All the studied γδT functional subsets had the expression of activity related receptors, and the ability of a rapid production of various amount of cytotoxicity related effectors following mitogen stimulation. Although IL-2 at high concentration suppressed the proliferation of CD4 T cells, it could promote the proliferation of γδT cells. The proliferated γδT cells were mainly CD27-CD45RA- effector cells. Discussion IL-2 within the clinical dose range could promote the proliferation of human peripheral blood γδT cells, which might have important biological significance in IL-2 based anti-tumor therapy.

Key words: interleukin 2, γδT cell, proliferation, phenotype