ELEVATED INTERLEUKIN-2 PRODUCTION BY CORD BLOOD MONONUCLEAR-CELLS FROM PREMATURE NEWBORNS

This study was undertaken to delineate the elements of the interleukin-2 (IL-2) system in premature newborns by quantitating IL-2 production and IL-2 receptor (IL-2R) expression and density in cord blood mononuclear cells (CBMC) from 19 premature (estimated gestational age = 27-36 weeks, mean = 33.7), but otherwise healthy, infants and 25 term newborns. Phytohemagglutinin (PHA)-induced IL-2 production by premature CBMC was significantly greater (p < 0.05) than that produced by term newborn CBMC with a mean value of 52.0 u/ml for prematures versus 18.2 u/ml for terms. The mean percentage of CBMC expressing PHA-induced cell-surface IL-2R was 23.4 and 23.0% while the IL-2R density per cell was 4.72 x 10(4) and 6.93 x 10(4) for premature and term newborns, respectively. PHA-induced proliferation was similar in both groups. These results show a significantly increased PHA-induced IL-2 production, but similar IL-2R expression, in CBMC from premature as compared to term newborns, demonstrating that the preterm newborn possesses a competent IL-2 system at birth.