Decreased expression of MMP-9 in CD8 cells in placenta with severe preeclampsia.

We compared the number of CD4-positive (CD4) and CD8-positive (CD8) cells in severe and non-severe preeclampsia (PE), and in normal pregnancy. We also evaluated the expression of matrix metalloproteinase 9 (MMP-9) in CD4 and CD8 cells. Immunohistochemistry for CD4 and CD8 was performed on the decidua basalis of 15 severe and 13 non-severe PE women and compared to decidual tissue of 19 normal pregnancies (control group). Co-expression of MMP-9 with CD8 and CD4 cells was determined by double immunofluorescence staining. The median number of CD8 cells/mm was significantly lower for the severe PE group than for the normal pregnancy group, as was the number of CD4 cells and MMP-9CD8 cells. No statistical difference was found between the non-severe PE group and the normal pregnancy group. The significant decrease of CD4, CD8 and MMP-9CD8 cells at the fetal-maternal interface only in the severe PE group suggests that immunological disorders play a role in the pathophysiology of severe PE.