The results suggest that decreasing seasonality of suicides could be a good marker of lowering rate of depression-related suicides in the population particularly among males.

Factors triggering hepcidin synthesis dominate 3 days after delivery. Studies are needed to assess the contribution of hepcidin to iron homeostasis during the periparturition period.

Cytokine production in activated T lymphocytes of the term neonate is reduced compared with adults. We aimed to characterize the calcium influx kinetics of activated T lymphocytes in the neonate and to test the functionality and expression of Kv1.3 and IKCa1 lymphocyte potassium channels, important regulators of calcium influx. We isolated lymphocytes from the peripheral blood of nine adults and cord blood of nine term neonates. We measured the calcium influx kinetics with flow cytometry in the T(h)1, T(h)2, CD4 and CD8 T-lymphocyte subsets activated with PHA. We determined the sensitivity of calcium influx to specific inhibitors of the Kv1.3 and IKCa1 channels. We also measured Kv1.3 channel expression using specific antibody. With the exception of the CD4 subset, calcium influx kinetics was decreased upon activation in neonatal T lymphocytes compared with adults. Neonatal T lymphocytes were found to be less sensitive to the specific inhibition of Kv1.3 and IKCa1 channels. The expression of Kv1.3 channels was higher on major T-lymphocyte subsets of newborns except for T(h)1 lymphocytes. Our findings suggest that the characteristics of short-term activation of major neonatal T-lymphocyte subsets are altered compared with adults. The altered function of neonatal lymphocyte potassium channels may contribute to this phenomenon.

Mitochondrial functions have a major impact on T-cell functionality. In this study we characterized whether mitochondrial function in the neonatal T-cells differs from that in the adult T-cells during short T-cell activation. Methods: We used flow cytometry methods to test mitochondrial mass and to monitor mitochondrial Ca 2+ levels, mitochondrial potential and superoxide generation in parallel with cytoplasmic Ca 2+ levels during phythohaemagglutinine-induced activation of CD4+ and CD8+ T-cells of 12 term neonates and 11 healthy adults. Results: Baseline mitochondrial mass of CD4+ and CD8+ cells was lower in the neonate than in the adult. In comparison with the adult, neonatal resting CD4+ T-cells had lower cytoplasmic Ca 2+ levels and this was associated with normal activation induced Ca 2+ -response. During short-term activation cytoplasmic Ca 2+-response was lower in neonatal than in adult CD8+ T-cells. Mitochondrial Ca 2+ uptake was increased in CD4+ neonatal T cells while it decreased in CD8+ T-cells. Mitochondrial depolarization was increased in CD4+ and decreased in CD8+ neonatal T-cells compared to adults. Superoxide generation was higher and equal in neonatal CD4+ and CD8+ cells, respectively, compared to the adult ones. Conclusion: Our data suggest that neonatal T-cells exhibit marked differences in mitochondrial function and superoxide generation compared to adult T-cells.

a b s t r a c tAlterations in the expression of B7 costimulatory molecules and their receptors, as well as differences in the tryptophan (TRP) catabolic pathway, may influence immunological reactivity of umbilical cord blood (UCB) compared with adult peripheral blood (APB) T lymphocytes. We determined the frequency of activated (CD11b þ ) monocytes expressing B7-1, B7-2, B7-H1, and B7-H2, and that of T cells and CD4 þ T helper cells expressing CD28, cytotoxic T lymphocyte antigen 4 (CTLA-4), programmed death-1 receptor, and inducible costimulator of T cells in UCB and APB samples using flow cytometry. We also examined the intracellular expression of indoleamine 2,3-dioxygenase (IDO) applying flow cytometry and plasma levels of TRP, kynurenine (KYN), and kynurenic acid using high-performance liquid chromatography. The level of CTLA-4 expression on CD4 cells was higher in UCB compared with in APB, indicating that the possibility of CD28-mediated costimulation may be decreased. The level of the corresponding costimulator molecule, B7-2, was also elevated. Therefore, this inhibitory relation may function to a higher extent in UCB than in APB. The plasma KYN to TRP (K/T) ratio was 2-fold higher in UCB compared with APB. However, the capacity of UCB monocytes to produce IDO compared with APB monocytes was lower, and reverse signaling via B7-2 in UCB monocytes was found to be immature, which suggests that the observed increase in K/T ratio may be due to placental, rather than fetal, overexpression of IDO in competent cells. These factors may all contribute to the previously observed reduced reactivity of UCB T lymphocytes compared to APB T cells.