Usefulness of PCR for Trypanosoma cruzi DNA in Endomyocardial Biopsies for Early Detection of Chagas' Disease Reactivation after Heart Transplantation
LA Benvenuti, A Roggerio, GH Coelho, A Fiorelli. University of São Paulo Medical School, São Paulo, SP, Brazil
Background: Chagas' disease is caused by the protozoan Trypanosoma cruzi. Around 20% of infected people develop a chronic, inflammatory cardiomyopathy which may progress to end-stage heart failure. After heart transplantation, Chagas' disease reactivation in the allograft (CDR) is characterized by inflammatory cell infiltration and presence of T. cruzi parasites in the myocardium. CDR must be distinguished from acute cellular rejection in endomyocardial biopsies (EMB); for this purpose, we routinely search for parasites in serial HE-stained sections and perform immunohistochemistry for T. cruzi antigens (IHC). In this study, we investigated the usefulness of PCR for T. cruzi DNA in EMB for the early detection of CDR.
Design: CDR was diagnosed in 6 heart-transplanted, chagasic patients (T. cruzi parasites detected in HE-stained sections in 5 EMB and positive IHC in 1 EMB). We examined retrospectively 18 EMB from those patients, collected up to 6 months before the diagnosis of CDR (pre-CDR group) and 15 EMB from 6 additional heart-transplanted, chagasic patients that had never presented clinical or pathological evidence of CDR (control group). Serial sections of the paraffin-embedded EMB were submitted to a PCR-based assay for T. cruzi DNA. We used two sets of primers: TCZI/II that amplifies a 188-bp repetitive nuclear sequence of T. cruzi DNA and S34/67 that amplifies a 122-bp sequence localized within the minirepeat of the parasite's kinetoplast minicircles (kDNA).
Results: The search for parasites in HE-stained sections and IHC resulted negative in all EMB of pre-CDR and control groups. The results of PCR for T. cruzi DNA are presented in the table. There was no statistical difference between pre-CDR and control groups, regarding the number of positive patients or the number of positive EMB (Fischer's exact test).
|Amplified DNA||Pts of pre-CDR group (n = 6)||EMB of pre-CDR group (n = 18)||Pts of control group (n = 6)||EMB of control group (n = 15)|
|Nuclear||1/6 (16.7%)||2/18 (11.1%)||0/6 (0%)||0/15 (0%)|
|kDNA||3/6 (50%)||6/18 (33.3%)||2/6 (33.3%)||4/15 (26.7%)|