Immunohistochemical characterization of the inflammatory infiltrate in placental Chagas' disease: A qualitative and quantitative analysis

Chagas' disease, a systemic illness endemic to some regions of South Americ a, is caused by the protozoan Trypanosoma cruzi. Transplacental infection m ay occur during any phase and cause fetal death. This study is the first to characterize the inflammatory cells in chagasic villitis by immunohistoche mistry. Paraffin sections of 8 placentas with villitis by T. cruzi (4 live births and 4 stillbirths), as well as 8 control placentas without inflammat ion, were stained with hematoxylin and eosin, monoclonal antibodies for CD4 5RO, CD20, CD45RO/OPD4, CD8, HNK1, CD15, MAC387, and CD68 proteins, and a p olyclonal antibody for S-100 protein. Quantification of positive cells was performed in 3 different high-power fields. In all cases of chagasic villit is, the inflammatory infiltrate was composed mainly of CD68+ macrophages, T lymphocytes, and a few natural killer cells. Among T cells, CD8+ cells out numbered CD4+ cells in all placentas (CD4+:CD8+ ratios ranged from 0.04 to 0.38). B cells were absent or rare. In stillbirths, villitis was diffuse an d severe with numerous T. cruzi, while in live births it was focal with few parasites. Other features that characterized villitis in stillbirths were 1) frequent trophoblastic necrosis, 2) presence of MAC387+ macrophages and CD15+ granulocytes attached to the sites of trophoblastic necrosis, 3) low CD4+: CD8+ ratios in most cases, 4) increased numbers of S-100 positive cel ls in the villous stroma. In conclusion, CD68+ macrophages and CD8+ T lymph ocytes were the major cell population in villitis caused by T. cruzi. Howev er, the pattern of inflammatory reaction differed between stillbirths and l ive births and was probably related to the number of parasites in the place ntal villi.