Summary
Cytoplasmic granule toxins are predominantly a membrane-disrupting protein known as perforin and a family of structurally related serine proteases (granzymes) are secreted by cytotoxic CD8+ T cells and together induce apoptosis of the target cell.
The aim of this study was to evaluate the expression of granzyme B and perforin in cytomegalovirus (CMV) and Ep stein- Barr virus (EBV) infected patients’ blood after kidney transplantation. For this purpose blood samples of 53 patients with kidney transplant and 20 healthy blood donors were collected.
Method. Expression of granzyme B and perforin was quantified by flow cytometry. The blastic transformation of lymphocytes as say was performed in parallel challenging T lymphocytes from 20 healthy donors. Phytohemoagglutinin (PHA) was used to stimulate CD8+ T cells.
Results. The comparison of the incidence of CMV and EBV infections among kidney recipients revealed that CMV infection was detected in the blood of 18 patients and EBV was found in the blood of 4 patients. Examination of CD8+ T lymphocyte granzyme B and perforin counts showed that the percentage of these proteins in kidney transplant patients with CMV or EBV infection was significantly 13–17% higher than in patients with out copies of the viruses. The blastic transformation of lymphocytes as say in the blood of healthy donors showed that statistically significantly higher number of CD8+ T lymphocyte granzyme B and perforin was ob tained after stimulation than before the stimulation. Unstimulated T lymphocytes showed 14% granzyme B and 8% perforin expression. Mitogen stimulation resulted 8% increase of granzyme B expression and 6% increase of perforin expression. Agerelated evaluation showed that the highest expression of granzyme B and perforin was found in the oldest group of patients and the lowest expression was found in the youngest group of patients.
Conclusions. Comparing the changes of granzyme B and perforin in kidney recipients and in healthy donors, a significant increase of granzyme B and perforin expression was observed in virus-infected patients than in healthy donors’ blood before and after stimulation with a non-specific mitogen. These data suggest that PHA-activated healthy human CD8+ T lymphocytes have lower expression of granzymes B and perforins than the same subpopulation of T lymphocytes in the blood of kidney recipients has. A remark able observation in this study was that the increasing expression of perforin and the tendentious increase in granzyme B were associated with agerelated changes in T lymphocyte subpopulations.
