Background: Despite morphologic differences of lymphocytes aggregation between nonrejection (0 on the International Society for Heart and Lung Transplantation [ISHLT] scale) and moderate focal cellular rejection (1a, ISHLT), genetic and clinical differences have not been shown in Cardiac Allograft Rejection Gene Observation (CARGO) studies. Therefore, we sought to compare the expression of selected antigens associated with apoptosis in heart transplant recipients in the context of grade 0 versus grade 1a cellular rejection episodes. We assessed the expression of annexin V, a nonspecific apoptosis marker, Bcl-2 as opposed to antiapoptotic activity of Bcl-xL and Bcl-xL/S.
Materials and methods: We retrospectively examined 17 heart transplant patients (2 women and 15 men) of overall mean age of 46.2 +/- 13.9 years and body mass index of 25.7 +/- 3.2. Ten biopsies showed rejection grade 0 and the other 10, grade 1a on the ISHLT scale, comprising groups A and B, respectively. Endomyocardial biopsy specimens were processed using routine immunohistochemical methods. The expression of apoptotic molecules was assessed according to the IHC method: 0, the lack of expression; 1, trace; 2, distinct; and 3, strong. A correlation was analyzed between particular molecular expressions.
Results: We observed a significant increase in Bcl-2 expression associated with rejection. The expression of other antigens did not show a significant tendency. No correlation was noted among group A, whereas in group B those were significant strong and negative correlations with Bcl-2 and Bcl-xL/S.
Conclusion: Bcl-2 expression corresponded to the morphologic progression of graft rejection as opposed to Bcl-xL/S activity.