PREMATURE PARTURITION IS CHARACTERIZED BY IN-UTERO ACTIVATION OF THE FETAL IMMUNE-SYSTEM

OBJECTIVE: At birth the fetus emerges from a sterile environment into a nonsterile one. This process is associated with activation of the fe tal immune system which protects the fetus against infection in the ne wborn period. We conducted this study to determine whether activation of the monocyte-neutrophil system occurs in fetuses before premature b irth. STUDY DESIGN: Forty patients in premature labor with intact memb ranes underwent cordocentesis for research purposes. Fetal blood was a nalyzed with the use of flow cytometry to measure the cell surface mar kers CD11c, CD13, CD15, and CD67, which are associated with monocyte a nd neutrophil activation, and CD14 and CD63, which were used as contro ls. RESULTS: Twenty-eight percent (11/40) of the infants were delivere d prematurely within 72 hours of entering the study while the remainde r were delivered at term. Our data clearly indicate that premature inf ants delivered within 72 hours had a higher percentage of CD11c, CD13, CD15, and CD67 than those delivered at term. In contrast, there were no significant differences in the percentages of CD14 acid CD63. CONCL USION: Activation of the monocyte-neutrophil system exists in fetuses destined for premature delivery. These findings indicate that prematur e parturition is associated with in utero immune system activation.