DETECTION OF HUMAN DEFENSINS IN THE PLACENTA

PROBLEM: The placenta is a highly selective barrier against the hemato genous dissemination of infectious agents. Despite the presence of see mingly intact physical and immunologic barriers, infections nonetheles s occur. These observations prompted the examination of placental tiss ue, amnion, and chorion for previously unrecognized protective mechani sms. METHOD OF STUDY: Messenger RNA from term placenta, amnion, and ch orion were reverse transcribed using a 3' RACE adapter. 3' rapid ampli fication of cDNA ends (RACE)-polymerase chain reaction (PCR) was condu cted on cDNA from these tissues to detect the presence of human defens ins. Southern analysis and partial sequence analysis were subsequently performed to confirm identity. RESULTS: PCR amplification of placenta l, amnion, and chorion cDNA yielded a 468-bp product and a weakly dete ctable band of 300 bp. Southern analysis demonstrated two correspondin g hybridizing bands in the placenta, amnion, and chorion but not from a negative cDNA control. Partial sequence analysis of the 468-bp produ ct from placenta confirmed the presence of either defensin 1 or 3 in h uman placenta, CONCLUSIONS: The human placenta, amnion, and chorion ex press defensins at the level of transcription. These findings suggest that a novel and previously unrecognized mechanism of protecting the f etus against infection may be present within these tissues.