Clinical management of short children with low serum immunoglobulin but no immunodeficiency features.

BACKGROUND: In children of different ages investigated for failure to thrive, low (below the cut-off for age) immunoglobulin (Ig) values can be detected, without any clinical evidence of humoral immunodeficiencies. To better characterize infants presenting with diminished immunoglobulin levels, we studied IgG subclasses, in vitro Ig production and B cell subpopulation. METHODS: We monitored 17 children (12 boys and five girls, age range 1-18 years) with low serum levels of one or more Ig isotypes but without any clinical or laboratory features of immunodeficiency. RESULTS: Low IgM levels were frequent (52.9%). During the follow up, six of 17 cases (35.3%) normalized their immunoglobulin levels. Frequently, in the observed patients, low levels of immunoglobulins were not limited to the period of infancy. In all patients, in vitro Ig production and B lymphocyte subpopulations were within normal ranges. CONCLUSIONS: We suggest a quantification of serum Ig levels in children who fail to thrive in order to identify patients with low Ig levels. These children should be monitored until Ig levels normalize to exclude any immunodeficiency status. Early recognition of children with persistent hypogammaglobulinemia would allow prompt and appropriate clinical interventions.

Age-related changes in intracellular TH1/TH2 cytokine production, immunoproliferative T lymphocyte response and natural killer cell activity in newborns, children and adults.

To evaluate the development of the neonatal immune system, we measured T lymphocyte response to Con A, intracellular IL-2, IL-4, IFN-gamma and IL-10 production, and natural killer cell (NKC) activity in 12 very preterm, 12 preterm and 20 term neonates, 10 children and 10 adults. Immunoproliferation to Con A was significantly lower in cord blood than in children or adults. The percentage of CD4+ lymphocytes was significantly higher in newborns while CD8+ cells were higher at older ages, with a resulting gradual decline of the CD4+/CD8+ ratio. The percentage of IL-2-producing CD4+ and CD8+ cells was higher in all newborn groups than in children and adults, while the percentage of IL-4-producing cells was higher for CD8+ and lower for CD4+ cells in cord blood than in children and adults. Neonates had substantially lower percentages of CD4+ and CD8+ IFN-gamma-producing cells. A significant negative correlation was observed between gestational age and IFN-gamma-CD4+-, IL-2-CD8+-, and IL-10- CD4+-producing cells. In addition, a positive correlation was found between gestational age and IL-10-CD8+-producing cells. Percentages of CD4+/CD45RA+ cells were higher and CD4+/CD45RO+ percentages were lower in newborns than in children and adults. NKC activity in infants was significantly correlated with gestational age and significantly impaired compared to children and adults. On the whole, these results suggest a gradual development of immunity during gestation and show significant immaturity of cellular immune response at birth. The reduction of NKC activity, the lower proliferative response of T cells, the reduced cytotoxic response and a dysregulated cytokine production may contribute to the neonatal increased risk of infection and to the low incidence of graft-versus-host disease after cord blood transplantation.