Background: The function of the allograft seems to be dependent on the level of regulatory lymphocytes including CD8+CD28- cells. This is a heterogonous population containing both suppressor (Ts) and cytotoxic cells (Tc). It is possible that adhesive molecules CD11b and CD57 can be helpful to distinguish between Ts and Tc subpopulations. The aim of this study was to evaluate the differences in the expression of CD11b and CD57 within CD8+CD28- population in renal allograft recipients with different immunosuppressive regimens (CsA or RAPA) and different graft's function.
Material/Methods: Peripheral blood was obtained from the healthy volunteers
and patients divided into four groups: CsA-Sta, RAPA-Sta, CsA-CR, RAPA-CR.
Sta - stable graft function; CR - chronic graft rejection; CsA - cyclosporine A,
azathioprine, prednisone; RAPA - rapamycin, prednisone. Peripheral blood
mononuclear cells were labelled with mouse anti-human mAbs conjugated with fluorochromes and analyzed by flow cytometry (FACSCalibur).
Results: In CsA-Sta group the expression of CD11b within CD8+CD28- population was lower than in the healthy volunteers. The expression of CD57 within CD8+CD28- population in RAPA-Sta group was higher than in the healthy volunteers, CsA-Sta and CsA-CR groups. In the group with the biggest variation in the number of HLA donor/recipients mismatches - CsA-CR, we observed some correlations between the number of HLA mismatches and the expression of CD11b and CD57 within CD8+CD28- population: positive for CD57 and HLA-DR, negative for CD11b and HLA-A, positive for CD11b and HLA-B.
Conclusions: The expression of CD11b and CD57 within CD8+CD28- population in renal allograft recipients seems to be dependent not only on the type of immunosuppressive regimen but also on the number of HLA mismatches between the donor and recipient. Therefore both of these factors can influence the ratio Ts: Tc in heterogonous CD8+CD28- population.

Keywords: Immunosuppression, Kidney Transplantation