Alterations in lymphocyte phenotype of infected newborns

Newborns, especially of lower gestational age, are more susceptible to infections because their immune system is immature and inexperienced. In order to investigate the characteristics of lymphocyte phenotype in neonates with early signs of perinatal infection, their lymphocyte populations were analyzed and compared to healthy newborns.
The cord blood lymphocytes from 14 infected and 52 uninfected newborns were labeled by monoclonal antibodies and counted using two-color flow cytometry. To exclude the effect of shorter gestation on the lymphocyte phenotype, of the infected newborns, who were all prematures, the analysis was carried out separately for prematures of less than 32 gestational weeks and for prematures of 32 - 37 weeks.
The percentages of T lymphocytes and both helper and cytotoxic T lymphocytes were significantly lower in the group of infected newborns, and the proportions of unlabeled cells were significantly increased in this group. There was no increase in CD45R0+CD4+ cell level in infected neonates, but the percentage of these cells was very low in both groups (1.1 and 1%).
The results were similar when only the preterm newborns of less than 32 gestational weeks were analyzed, with the exception of T helper lymphocytes which did not differ between the groups. These differences were not significant for the higher-gestation prematures, although the same tendencies were evident.
The higher proportion of unlabeled lymphocytes in infected newborns reflects the reduced expression of cell surface molecules and means a more immature and less efficient immune system. Cells CD45R0+CD4+ cannot be used as a marker of infection in neonates
Category: Clinical observations - professional paper
Volume: Vol. 43, No 3, july - september 1999
Authors: E. Juretić, T. Tkalčević, V. Vukelić, B. Užarević, M. Petrovečki
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