Comparative histopathology of endomyocardial biopsies in chagasic and non-chagasic heart transplant recipients

Background: Heart transplantation has been an option for the treatment of c hagasic (C) cardiomyopathy despite difficulties concerning the control of r ejection and reactivation. The parasite-host interaction under the influenc e of immunosuppressive therapy may affect the immunological response to the graft in a pattern different from that in non-chagasic (NC) patients. The aim of this study was to compare the major histopathological features in he art: transplantation in C and NC patients. Methods: We studied 293 endomyocardial biopsies from two groups of heart tr ansplanted patients, including 18 C and 15 NC. Both groups had identical su rgical and clinical procedure except immunosuppressive therapy was lower in C patients. The histopathological parameters evaluated were the Quilty eff ect, rejection, C myocarditis reactivation, fibrosis, hypertrophy, and isch emia. In addition, lymphocytic cellular infiltration of myocarditis due to rejection or reactivation was immunophenotyped in the biopsies of both grou ps with rejection grades 3 to 4, in biopsies with signs of reactivation, an d in fragments of the receptor heart with chronic C myocarditis. A search f or Trypanosoma cruzi was performed in all biopsies in the C group in which lymphocyte immunophenotyping was done. We used immunofluorescence and confo cal microscopy. Results: The Quilty effect was present in 23% of the biopsies, involving 69 .7% of the patients without a significant difference between groups (p = 0. 509). Rejection was frequently observed in biopsies with the Quilty effect and the effect often recurred in the same patient. Rejection grades 3 to 4 was more frequent in the C group (p = 0,023). There were 5 episodes of Chag as' disease reactivation with myocarditis in 2 cases. The mean numbers of C D8+ and CD4+ T cells, and the CD4+-to-CD8+ ratio were similar for rejection in both groups (p > 0.05), while the CD4+-to-CD8+ ratio was significantly lower in chronic C myocarditis compared to rejection in the C group (p = 0. 043). There was no significant difference in ischemic damage or interstitia l fibrosis in the groups but there was a higher frequency of hypertrophy in the NC group (p = 0.007). Conclusions: The histopathological features of heart transplantation in C p atients did not differ from that in NC patients in regard to the Quilty eff ect, development of myocardial fibrosis and ischemia. However, the higher i nvolvement of the C group for rejection grades 3 to 4 suggested higher susc eptibility to this event. The similarity of the lymphocytic cellular compos ition for rejection in both groups indicates that C patients respond to imm unological stimulus in a similar pattern as NC patients.