Placental cellular immune response in women infected with human parvovirusB19 during pregnancy

Human parvovirus B19 can cause congenital infection with variable morbidity and mortality in the fetus and neonate. Although much information exists o n the B19-specific antibody response in pregnant women, little information is available describing the cell-mediated immune (CMI) response at the mate rnal-fetal interface. The focus of this study was to characterize the CMI r esponse within placentas from women who seroconverted to B19 during their p regnancies and compare it to controls. Immunohistochemical techniques were used to identify the various immune cells and the inflammatory cytokine pre sent within placental tissue sections, Group 1 consisted of placentas from 25 women whose pregnancies were complicated by B19 infection; 6 women with good outcome (near-term or term delivery), and 19 with poor outcome (sponta neous abortion, nonimmune hydrops fetalis, or fetal death). Group 2 consist ed of placentas from 20 women whose pregnancies were complicated with nonim mune hydrops fetalis of known, noninfectious etiology, Group 3 consisted of placentas from eight women whose pregnancies ended in either term delivery or elective abortion. The results of the study revealed a statistically si gnificant increase in the number of CD3-positive T cells present within pla centas from group 1 compared to group 2 or 3 (13.3 versus 2 and 1, respecti vely) (P < 0.001), In addition, the inflammatory cytokine interleukin 2 was detected in every placenta within group 1 but was absent from all placenta s evaluated from groups 2 and 3. Together, these findings' demonstrate evid ence for an inflammation-mediated cellular immune response within placentas from women whose pregnancies are complicated with B19 infection.