LOW CD3-INDUCED INTERLEUKIN-2 PRODUCTION CORRELATES WITH DECREASED REACTIVE OXYGEN INTERMEDIATE FORMATION IN NEONATAL T-CELLS(CD28)

The capacity of neonatal T cells to secrete interleukin-2 (IL-2) has b een reported to be variable. We analysed IL-2 production in purified n eonatal and adult T cells using polyclonal activator phorbol ester + c alcium ionophore (PDBu + iono) or receptor-mediated anti-CD3/anti-CD3anti-CD28 stimulation. PDBu+iono induced equally high IL-2 levels in b oth groups and, when stimulated with plate-bound anti-CD3 monoclonal a ntibody (mAb), the IL-2 secretion by neonatal cells was undetectable a nd adult cells produced low amounts of IL-2 (mean 331 +/- 86 pg/ml). T he addition of anti-CD28 mAb to anti-CD3-stimulated cells markedly inc reased IL-2 production in both cell types, but levels of IL-2 in neona tal T cells remained clearly lower than those of adult T cells (respec tive mean values: 385 +/- 109 pg/ml and 4494 +/- 1199 pg/ml). As NF-ka ppa B is a critical transcription factor in the control of IL-2 expres sion, we next analysed its nuclear translocation in neonatal and adult T cells using the electrophoretic mobility shift assay and, because i nduction of reactive oxygen intermediates (ROI) is required for the ac tivation of NF-kappa B, we also analysed levels of intracellular ROI i n these cells using the ROI-reactive fluorochrome DCFH-DA and flow cyt ometry. In neonatal T cells NF-kappa B activation and ROI formation af ter anti-CD3 stimulation were low compared with adult T cells and, alt hough addition of anti-CD28 mAb increased induction of NF-kappa B and ROI formation, levels similar to those of adults were not achieved. Af ter PDBu+iono stimulation, the cells showed similar ROI formation and IL-2 secretion. Our results suggest that reduced IL-2 production by ne onatal T cells is specific for anti-CD3 and anti-CD3 + anti-CD28-media ted stimulation and that these activators cannot effectively activate the ROI-NF-kappa B signalling pathway in neonatal T cells.