The activation of lymphocytes through the T cell receptor is a complex process involving multiple signalling pathways which lead to the translocation of several DNA binding proteins to the nucleus and the initiation of cytokine gene transcription. The outcome of this process is the secretion of IL-2, which plays a central role in T cell proliferation. The products of thec-fos, and c-jun oncogenes as well as the transcription factor NFκB are all known to regulate IL-2 transcription after engagement of the T cell receptor. We hypothesized that the well-described defects in fetal and cord blood IL-2 expression might result from lack of expression of one or more of these factors.

Fetal umbilical cord blood samples obtained by ultrasound-guided cordocentesis and cord bloods from healthy term newborns were examined. Total RNA was extracted from 200 μl whole blood and reverse transcription was accomplished using 2.0 μl total RNA. Resultant cDNA's were subjected to PCR analysis for c-fos, c-jun, NFκB (p50 subunit), and β actin.

In all, 17 fetal samples (gestational age range = 21-37 weeks) and cord bloods from 7 term infants were sampled. All samples were positive for β actin. All seven term cord blood samples showed c-jun mRNA expression, and 5 of the 7 were positive for c-fos mRNA. All 5 of the term cord bloods analyzed for NFκB expression were positive. Fetal samples gave comparable results. Fifteen of the 17 samples were positive forc-jun mRNA, 16 of 17 were positive for c-fos, and 14 of 15 were positive for NFκ B. There was no obvious correlation between gestational age and absence of mRNA for any of the transcription factor mRNA's.

We conclude that c-jun, c-fos, and NFκB mRNA's are constitutively expressed in the majority of fetal and cord blood samples. Thus, the defects in IL-2 secretion seen in fetal and cord blood lymphocytes are probably not due to absence of these factors. One cannot conclude, however, that these factors are regulated as they are in adult lymphocytes. Experiments to examine this issue are under way in our laboratory.