Phototherapy for neonatal hyperbilirubinemia affects cytokine production by peripheral blood mononuclear cells

The capacity of peripheral blood mononuclear cells (PBMC) to produce interl eukin (IL) IL-1 beta, IL-2, IL-3, IL-6, IL-10 and tumor necrosis factor-alp ha (TNF alpha.) was examined in term newborns with hyperbilirubinemia after 24 hours' exposure to phototherapy (wave length 425-475 nm). The results w ere compared with those fi om untreated neonates. Fifty newborns spontaneou sly delivered at terrm were included in the study. Blood samples were colle cted from 20 newborns before and 24 h after phototherapy. The control group consisted of 30 neonates examined on two consecutive days, PBMC isolated f rom blood samples were incubated in vitro for cytokine production. The conc entration of cytokines in the supernatants was tested using ELISA kits: (fo r IL-1 beta, IL-6, IL-10 and TNF alpha), or by bioassays (for IL-2 and IL-3 ). Phototherapy caused a 70% increase in IL-2 secretion (123 +/- 27 vs 208 +/- 30 units/ml. P < 0.01) and 56% in IL-10 production (1.07 +/- 0.19 vs 1. 67 +/- 0.33 ng/ml, P < 0.03), whereas the spontaneous secretion of IL-1 bet a was reduced by 43% (13.7 +/- 2.3 vs 7.3 +/- 1.7 ng/ml, P < 0.02). In the control group the secretion of these cytokines was similar on the two conse cutive days and did not differ significantly from secretion in the other gr oup before phototherapy. On the other hand, lipopolysaccharide induced TNF alpha production was higher on the second day in the two groups of newborns irrespective of phototherapy (388 +/- 58 vs 683 +/- 88 pg/ml, P < 0.001, i n the control group and 384 +/- 75 vs 588 +/- 91, P < 0.05, before and afte r phototherapy). The synthesis of IL-3 and IL-6 did not change significantl y between the two days of the study. The results demonstrate that in additi on to the well-known nn positive effect of phototherapy on the neonate seru m bilirubin level. this treatment affects the function of the immune system in newborns via alterations in cytokine production.