Introduction: Ovine hydatidosis (OH; Echinococcus granulosus) is endemic in several European
countries surrounding the Mediterranean basin. It has been reported that early, establishment-phase
cysts stimulate a Th1-type immune response, while established phase cysts are associated with a
Th2, immuno-suppressive type profile. The aim of the present study was to differentiate and enumerate
T cell sub-populations present in the adventitia in established cysts from E. granulosus-naturally
infected sheep.
Materials and Methods: A total of 18 established cysts were obtained from naturally infected
sheep. Samples were frozen and 5 μm-thick serial sections were stained with anti-CD4, anti-CD8
and anti-Foxp3 monoclonal antibodies. Stained tissue sections were analyzed at 40× magnification.
Positive cells were enumerated in five consecutive fields of the adventitial layer of the cyst. Three
co-authors performed blinded, independent enumeration and mean values ± standard deviations,
were calculated. Wilcoxon and Mann–Whitney tests for non-parametric distribution between CD4+
and CD8+ cells were performed and p-Values less than 0.01 were considered to be significant.
Results: In all except 5 cyst, the number of CD4+ T lymphocytes was significantly higher (p = 0.009)
than CD8+ cells. Foxp3+ cells were present in 17 cysts and made up approximately 35% of total T
cell counts in those cysts.
Conclusions: The results of the present study may contribute to identifying the immunological features
involved during the different developmental stages of Cystic Echinococcosis (CE), including
early establishment. Furthermore, the understanding of established-phase associated immunity
may offer insights into immunotherapeutic strategies in human CE
