The study of the in-situ
cellular immune response is very important for the
understanding of different
liver infections. In the present study, 53
liver samples obtained by viscerotomy from
patients who died during the
course of jungle
yellow fever were analyzed. The
diagnosis was confirmed by
serology, viral isolation and
virus-specific
immunohistochemistry. The specimens were analyzed by
immunohistochemistry using specific
antibodies for
apoptosis, CD45RO, CD4, CD8, CD20, S100, CD57 and CD68.
Quantitative analysis of the labeling pattern showed a clear predominance of the different
phenotypes in the portal tract and midzone region of the acini. There was a predominance of T CD4+
lymphocytes, accompanied by the presence of T CD8+
lymphocytes,
natural killer cells (CD57),
macrophages and
antigen-presenting cells (S100). The disproportion between the intensity of
inflammation and the degree of hepatic
injury was probably due to the intense apoptotic component, which classically does not induce an inflammatory response. The present study demonstrates that, despite the disproportion between
injury and
inflammation, the
cellular immune response plays an important
role in the
pathogenesis of the hepatocytic
injury observed in
yellow fever, probably as a result of cytolytic actions through mechanisms involving MHC II and the activation of
Fas receptors and
granzymes/perforins...(AU)