Follicular bronchiolitis as phenotype associated with CD25 deficiency.

Regulatory T cells [Tregs ; CD4(+) CD25(+) forkhead box protein 3 (FoxP3(+) )] are subsets of T cells involved in the maintenance of peripheral self-tolerance by actively suppressing the activation and expansion of autoreactive T cells. Signalling through the interleukin-2 receptor (IL-2R) contributes to T cell tolerance by controlling three important aspects of regulatory T cell (Treg ) biology. CD25 is the α-chain of the IL-2R that, in concert with the ß-chain and γ-chain, constitutes the complete IL-2R. CD25 contributes only to IL-2 binding affinity but not to the recruitment of signalling molecules. However, its importance in the development of a normal immune response is emphasized by the finding that a truncation mutant of CD25 results in an immunodeficiency in humans characterized by an increased susceptibility to viral, bacterial and fungal infections. In 1997, Sharfe et al. described an infant with severe bacterial, viral and fungal infections. Counts of autologous T lymphocytes were moderately low, T cells displayed a weak proliferative response to mitogens in vitro and the patient displayed no rejection of an allogeneic skin graft. However, unlike children with severe combined immunodeficiency (SCID), besides not having circulating T cells, the patient also developed peripheral lymphocytic proliferation and autoimmune primary biliary cirrhosis. We present the first female Argentine patient with mutation in CD25 associated with chronic and severe inflammatory lung disease (follicular bronchiolitis with lymphocyte hyperplasia), eczema and infections. She has no expression of CD25 on CD4(+) T cells and an extremely low amount of Tregs . The molecular study confirmed homozygous missense mutation in the alpha subunit of the IL-2 receptor (CD25αR) (c. 122 a > c; p. Y41S).

Utility of new mature erythrocyte and reticulocyte indices in screening for iron-deficiency anemia in a pediatric population.

INTRODUCTION: Iron-deficient erythropoiesis attributable to nutritional deficiency is the most common cause of anemia in early childhood. Beckman Coulter has proposed new parameters: red blood cell size factor (RSf) and low hemoglobin density (LHD%). [Formula: see text] The aims of the present communication were to establish reference ranges (RR) for RSf and LHD% in a healthy pediatric population; to evaluate clinical utility of these parameters in the diagnosis of iron-deficiency anemia (IDA); and to compare RSf and LHD% with RET-He. METHODS: Two hundred healthy infants and 51 with IDA were analyzed on Coulter LH750 and Sysmex XT2000i analyzers. RESULTS: RR for RSf in children aged 0.5-6 years, 82.2-102.0 and 83.7-103.1 fl in the group aged 6-18 years. RR for LHD% was 1.1-9.0%. ROC analysis for RSf and LHD% in the diagnosis of IDA showed an AUC 0.8460 and 0.8654, respectively. The best RSf value to detect a restricted erythropoiesis was 89fl, sensitivity 92%, specificity 81%. LHD% optimal cutoff point was 6.0%, sensitivity 80%, and specificity 88%. Good correlation was observed between these parameters with Ret-He, r = 0.888 and r = -0.790, respectively. CONCLUSION: RSf and LHD% could be useful tools in the screening of IDA. These parameters can be obtained in the course of routine blood counts, with no additional cost or need for more blood sampling.