Flow cytometric analysis of lymphocyte subpopulations in infants with congenital heart disease

T cell receptor repertoire and function in patients with DiGeorge syndrome and velocardiofacial syndrome

DiGeorge syndrome (DGS) and velocardiofacial syndrome (VCFS) are associated with chromosome 22q11.2 deletion. Limited information is available on the T cell receptor (TCR) Vbeta repertoire. We therefore investigated TCR Vbeta families in lymphocytes isolated from blood and thymic samples of seven patients with DGS and seven patients with VCFS, all with 22q11.2 deletion. We also studied activities related to TCR signalling including in vitro proliferation, anti-CD3-induced protein tyrosine phosphorylation, and susceptibility to apoptosis. Reduced CD3+ T cells were observed in most patients. Spontaneous improvement of T cell numbers was detected in patients, 3 years after the first study. Analysis of CD4+ and CD8+ TCR Vbeta repertoire in peripheral and thymic cells showed a normal distribution of populations even if occasional deletions were observed. Lymphoproliferative responses to mitogens were comparable to controls as well as anti-CD3-induced protein tyrosine phosphorylation. Increased anti-CD3-mediated apoptosis was observed in thymic cells. Our data support the idea that in patients surviving the correction of cardiac anomalies, the immune defect appears milder than originally thought, suggesting development of a normal repertoire of mature T cells.

Lymphocyte subpopulations in healthy newborn infants: comparison of cord blood values with values five days after birth

Significant differences (p < 0.0001) were demonstrated in lymphocyte subpopulations both in cord blood and in venous blood samples obtained at day 5 from the same healthy infants. Numbers of T lymphocytes increased, especially CD4+/CD45RA+ cells, whereas numbers of B lymphocytes and natural killer cells decreased without changes in CD8+ and other cytotoxic cells.

Age-related changes in human blood lymphocyte subpopulations

Flow cytometric analysis of major lymphocyte populations and their subsets reveals age-related changes in the cellular human immune system. Immunophenotypic markers were evaluated in 110 normal pediatric subjects, divided into groups of newborn infants, infants aged 2 days to 11 months, and children aged 1 to 6 years and 7 to 17 years; results were then compared with those obtained from 101 normal adults aged 18 to 70 years. Comparisons among age groups from newborn infants through adults reveal progressive declines in the absolute numbers of leukocytes, total lymphocytes, and T, B, and natural killer (NK) cells. The percentages of T cells within the total lymphocyte population increase with age, in both CD4+ and CD8+ subsets. Percentages of B and NK cells are higher in newborn infants than in adults. The expression of the activation markers interleukin-2R and HLA-DR on T cells increases with age, as does the NK-associated expression of CD57 on CD8 cells. The proportions of B lymphocytes that coexpress CD5 or CDw78 decrease with age, whereas expression of Leu-8 and CD23 increases. The proportion of CD4 cells bearing the CD45RA and Leu-8 markers is consistently lower in adults than in children. These data may serve as a reference range for studies of pediatric subjects.