Abstract
INTRODUCTION: The
detection of
Trypanosoma cruzi in
tissue samples is important in many situations, such as testing of the reactivation of the
infection . The
detection of T. cruzi nests in endomyocardial
biopsies (EMB) may be useful to evaluate
graft rejection . Given their scarcity, such nests are not routinely identified. To increase the
diagnosis sensitivity ,
immunohistochemistry (IHC) may serve as a promising strategy. Here, we validate an antiserum for the
detection of T. cruzi
infection by IHC.
METHODS: We used 1) positive controls (PCs) - 13 EMB, 12
skin biopsies , and 1
heart with T. cruzi nests as sections stained with
hematoxylin and
eosin (HE); 2) negative controls - a) 10 explant
hearts and 10 EMB with no amastigote nests or clinical/
laboratory signs of chagasic
infection ; and b) eight samples with
leishmaniasis ,
toxoplasmosis , or
histoplasmosis ; and 3) Cases - 31 EMB of chagasic
patients with no
parasite nests in HE sections but detected positive for T. cruzi
DNA by
polymerase chain reaction . As a primary antibody, a hyperimmune
serum from T. cruzi-infected
rabbits was used.
RESULTS: IHC results were positive for 21 of 26 PCs (80.8%) and one case of
cutaneous leishmaniasis . In 4 of 31 cases, IHC revealed nests (12.9%), which were undetected by conventional histological examination.
CONCLUSIONS: This study shows that IHC with the tested antiserum increases the
sensitivity of the
diagnosis and may be recommended for routine use in EMB analyses of cardiac
transplant patients with
Chagas disease .