Peripheral blood B lymphocytes in infancy and childhood

Abnormalities in lymphocyte populations in infants with neural crest cardiovascular defects

The DiGeorge syndrome has been associated with various immune deficits. Embryologically, defects of the neural crest are associated with conotruncal and aortic arch abnormalities. The objective of this study was to determine if children with neural crest congenital heart defects can have subtle but significant immunodeficiencies. Complete blood counts with differential counts and a standard lymphocyte immunophenotyping panel of selected monoclonal antibodies were performed on peripheral blood from 20 children with neural crest cardiac disease and 34 normal newborns. The children with cardiac disease were grouped as survivors and nonsurvivors. The mean total white blood cell count was similar for all groups, but the percent lymphocytes was significantly less in the nonsurvivors than in the survivors and normal newborns (p < 0. 02). The lymphocyte subsets affected were CD2, CD3, and CD4. When the cardiac patients were compared to the normal newborns, again differences in lymphocyte subsets CD2, CD3, and CD4 were seen. When comparing nonsurvivors with survivors, the mean percentages of the CD2, CD3, and CD4 T lymphocyte markers, as well as the mean lymphocyte, B cell (CD20), and natural killer cell (CD16) percentages were all lower in the nonsurvivors. It was concluded that abnormalities in specific lymphocyte populations and their subsets may be predictors of infants at greatest risk for immunodeficiency complications. Therefore children with neural crest cardiac defects should have evaluations of lymphocyte subsets at birth and be treated as if potentially immunodeficient.

Analysis of proliferating lymphocyte subpopulations in newborns and adults

Surface markers of peripheral lymphocyte subpopulations were determined before and after in vitro stimulation of neonatal and adult mononuclear cells with phytohaemagglutinin (PHA) and pokeweed mitogen (PWM). The type of cell responding to each mitogen was identified by a method combining autoradiography and the peroxidase-antiperoxidase (PAP) staining method. In comparison with adults, there is a lower proportion of OKT3-positive lymphocytes in neonates (43% vs. 72%). Analysis of lymphocyte subpopulations after stimulating mononuclear cells with PHA and PWM showed that in neonates nearly the same percentages of OKT4-and OKT8-positive proliferating cells (43% and 40%, respectively) could be observed, whereas in the proliferating cells from the adults, the OKT8 surface marker predominated (41% vs. 18%).

Identification of lymphocyte subsets in the newborn using a variety of monoclonal antibodies

Using a small sample of peripheral venous blood, the normal range for lymphocyte subpopulations (T-cell, B-cell, T-suppressor cell, and T-helper cell) was defined in non-infected preterm and term infants. Lymphocyte subsets were identified using a variety of monoclonal antisera, and analysis was performed using a fluorescent activated cell sorter. Such methods allow an objective assessment of absolute numbers of cells per unit volume of whole blood. There was no significant difference in absolute numbers of lymphocyte subsets between term and preterm appropriate for gestational age (AGA) infants. Infants who were small for gestational age (SGA) had a significant deficiency in absolute numbers of total T-cells, helper and inducer T-lymphocytes, and B-cells compared with both term and preterm AGA infants. All newborn infants (term and preterm; AGA and SGA) had a highly significant increase in absolute numbers of both helper and suppressor T-lymphocytes compared with normal adults.

Comparison of RNA and DNA synthesis, spontaneous and PHa induced, between blood lymphoid cells of newborn infants, older infants, and adults. A study of scintillation counting and by autoradiography

Spontaneous and PHA induced RNA and DNA synthesis was measured qualitatively by autoradiography and quantitatively by scintillation counting in blood lymphoic cells of newborn infants, older infants, and adults. Spontaneous RNA synthesis was found in transitional cells, large phagocytic lymphoid cells and lymphocytes. Transitional cells and phagocytic lymphoid cells also synthesized DNA spontaneously. Quantitatively, spontaneous RNA synthesis was active in both newborn infants and in adults, but significantly less so in older infants. PHA stimulation for 18 h increased RNA synthesis significantly in blood lymphoid cells of newborn infants and adults, and to a much lesser but still significant degree in older infants. Spontaneous DNA synthesis was significantly greater in newborn infants than in older infants and adults. PHA stimulation for 18 h had no effect on thymidine incorporation in any of the groups studied.

Lymphocyte markers in newborn infants

Purified peripheral blood lymphocytes from 20 newborn infants and 12 adults have been studied for the presence of surface markers. Adults and infants did not differ in the percentage of sheep RBC-binding cells (means 58-65%) or in Ig-bearing cells measured by the mixed antiglobulin reaction (means 7.2-11.6%). However, newborn infants had a significantly lower percentage of lymphocytes binding Fc of IgG (mean 10.4%) as compared to adults (mean 17.2%). No overall correlation between plasma Ig levels and Ig-bearing lymphocytes was found but a single infant with increased plasma IgA also showed the highest level of Ig-bearing lymphocytes among all infants.

B, T and null lymphocytes in newborn infants and their mothers

Estimation of B, T and null cells were performed on 29 newborn healthy babies and 16 mothers. The lymphocytes were isolated from peripheral venous blood, which is considered to be more representative of the immune state in the newborn than the cord blood. B lymphocytes were estimated by cytofluorometric measurements, T lymphocytes by sheep red blood cell rosette technique, (SRBC-R). Combined immunofluorescence and SRBC-R technique revealed the null cells. In the newborn babies the amount of B and T cells were found to be diminished. In the mothers the amount of B lymphocytes were low compared with normal adults. The rather high null cell percentage found in the babies might represent immature precursor cells. Mothers seem to be immuno-depressed as reflected in the low amount of B cells.

Derangements of immunoglobulin levels, phytohemagglutinin responsiveness and T and B cell markers in Down's syndrome at different ages

Immunologic studies were performed in 83 patients with Down's Syndrome (DS) in ages ranging from a few months to 30 years and 76 karyotypically normal age-matched controls. The results show that both thymus-dependent and independent functions were impaired in DS with a characteristic age sequence. Serum immunoglobulin levels were normal in children with DS less then 5 years old; after 6 years of age a definite hyperglobulinemia of the IgG and IgA type was observed. A slight decrease in IgM was observed between 16 and 25 years of age. In subjects with DS lymphocyte phytohemagglutinin responsiveness was in the normal range during the first decade but it decreased thereafter progressively; the percentage and absolute number of peripheral blood lymphocytes forming "spontaneous rosettes" with sheep erythrocytes were abnormally low at all ages including infancy; the number of circulating lymphocytes with a high density of surface immunoglobulins was always in the normal range.