Assays of lymphocyte subpopulations and function have been applied to cells from the cord blood of twenty-four infants. The results are compared with those obtained in healthy adults. T cells, assayed by spontaneous rosette formation with sheep red blood cells (E rosettes) were present in lower proportion in cord (53%) than in adult blood (65%). There was a higher proportion of lymphocytes bearing stainable immunoglobulin in cord (32%) than in adult blood (22%). From the blood lymphocyte counts it was calculated that both T and B lymphocytes are present in greater numbers in the newborn infants' blood than in adults. Comparison of DNA synthesis showed that cord blood leucocytes had a higher spontaneous rate, but there were only minor differences in the lymphocyte mitotic response to phytohaemagglutinin (PHA). The response of cord blood lymphocytes was slightly lower to a submaximal stimulus and higher to a maximal stimulus. There was a correlation between the submaximal response and the proportion of E rosetting cells.
The most striking differences between infant and adult blood lymphocytes were in their cytotoxic activity against homologous target cells (Chang cells). Antibody-dependent cytotoxicity (K-cell activity) was readily detected using cord blood leucocytes, though it was lower than that of adult cells. PHA-induced cytotoxicity was very low in all cord blood samples, and in many cases was almost unmeasurable. This dissociation between the two types of cytotoxic activity is consistent with other evidence that they may be mediated by different cell types.
The assays were also applied to blood samples taken from five mothers of tested infants immediately after delivery. While some differences from normal adults were found with the mothers' lymphocytes they did not mirror those of the cord blood samples. This suggests that the pattern found for cord blood lymphocytes is not due to maternal factors crossing the placenta.
Concentrations of immunoglobulins and anti-Escherichia coli antibody were studied longitudinally in tracheobronchial aspirates from 33 premature intubated neonates, median gestational age 27 weeks. Aspirates collected at birth contained IgG, IgA, and IgM in 100%, 93%, and 79% of samples, respectively. The median IgA concentration at birth was 0.7 micrograms/mg total protein and increased to 5.8 micrograms/mg protein by the sixth week. IgG and IgM antibodies to E coli were present in 90% and 30%, respectively, of tracheobronchial aspirates collected at birth. Samples from three of 28 neonates (11%) contained IgA anti-E coli antibody at birth, and the proportion with IgA antibody rose to 50% during the sixth week. Secretory component associated IgA and IgM were detectable in samples tested at birth and at 4 weeks of age, and secretory component associated anti-E coli antibody was present in aspirates from three of nine neonates studied at 4 weeks of age, but had not been detectable at birth.
We report two premature infants with respiratory distress syndrome who developed central diabetes insipidus following intracranial insult. There was no midline defect noted both radiologically and clinically. Pituitary hormone profiles were within normal limits in the infants. Intranasal desmopressin was prescribed to both of them with prompt response which was shown by a reduction of urine output and normalization of serum sodium level with urine concentrating ability. The dose and administration method of desmopressin were repeatedly adjusted. Central diabetes insipidus did not resolve even after the complete resolution of intraventricular haemorrhage in one of the babies.
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