TRANSFER OF CYTOKINES THROUGH HUMAN FETAL MEMBRANES

Intact human fetal membranes (amnion, chorion and decidua) were incuba ted with I-125-labelled cytokines added to the fetal or maternal sides of the membrane. The transfer of I-125-labelled interleukin-6 (IL-6), I-125-labelled tumour necrosis factor cr. (TNF-alpha), I-125-labelled interleukin-1 alpha (IL-1 alpha) and I-125-labelled interleukin-1 bet a (IL-1 beta) was determined by measurement of radioactivity in a gamm a counter and the integrity of the cytokines was assessed by acid prec ipitation and by radioimmunoassay. IL-1 alpha and IL-1 beta were trans ferred through human fetal membranes in both feto-maternal and materno -fetal directions at similar rates. Only 2-4% of the cytokine original ly added appeared to be intact on the opposing side of the membrane af ter 24 h of culture. Transfer of intact TNF-alpha (5-7%) and IL-6 (8-1 7%) was greater than that of the IL-I isomers. Low but variable amount s of the four cytokines tested may be transferred through the human fe tal membrane. This finding suggested that concentrations of cytokines in amniotic fluid would not reflect those produced by decidua if the f etal membranes are intact.