Abstract 51

Introduction IL-1β and IL-1ra in cross sectional studies are higher in neonatal sepsis compared to controls, but the background concentrations have not been studied. Longitudinal changes in the concentrations of IL-1β, IL-1 receptor antagonist (IL-1ra) and the soluble form of the type II receptor of IL-1 (IL-1sRII) were measured to determine the IL-1β bioactivity in babies admitted to the NNU. Populations of differing gestation and outcome were compared.

Methods Serum concentrations of each ligand were measured at 7 predetermined times over 3 weeks in 26 neonates. Times of acute inflammation were avoided.

Results Neonates <28 weeks gestation (n=14) had greater median values (range) of each cytokine than those >28wk {IL-1β=1.2 (undetectable (UD)-5.74) vs 0.4 (UD-2.99) (p<0.05), IL-1ra=12000 (2040-39900) vs 3100 (680-23700) (p<0.05), IL-1sRII = 21000 (14400-34800) vs 16000 (11500-17900) (p=0.3)}. Of the neonates <33 weeks gestation (n=19) those who developed chronic lung disease (n=11) had higher values than those who did not {IL-1β=1.6 (0.4-16.7) vs 0.37 (UD-2.83) (p<0.01), IL-1ra - 14000 (2370-50000) vs 2700 (620-18500) (p<0.01), IL-1sRII=21000 (13700-29500) vs 20000 (16400-29200) (p=0.3)}.

Conclusions Sicker neonates had consistently higher concentrations of IL-1β and IL-1ra suggesting that they are in a more persistent inflammatory state.