RESUMEN
Human CD8(+)CD28(-) T suppressor cells were previously shown to be involved in the control of the immune response to transplanted allografts. It seems essential to examine how immunosuppressive drugs influence these cells. However, the CD8(+)CD28(-) population contains both suppressor (Ts) and cytotoxic (Tc) T cells, and the phenotype of the Ts subpopulation has not been identified explicitly. It is proposed that the transcription factor FOXP3 may be helpful in distinguishing the Ts and Tc subpopulations. The aim of this study was to evaluate the influence of the immunosuppressive drugs cyclosporine A (CsA) and rapamycin (RAPA) on the level, suppressor properties, and phenotype of human CD8(+)CD28(-) T cells in vitro. The model used was the mixed leukocyte reaction performed with peripheral blood mononuclear cells from healthy volunteers. It was observed that CD8(+)CD28(-) T cells from cultures with CsA or RAPA had similar suppressor properties to cells from control cultures, although the drugs influenced the expression of FOXP3. CsA and RAPA did not interfere with the suppressor properties of human CD8(+)CD28(-) T cells in vitro, although they affected the expression of the FOXP3 molecule.