[Analysis of lymphocyte immunophenotypes in neonates]. / Analiza imunofenotipova limfocita novorodencadi.

Immune system development is not completed at the end of gestation, so newborns are not fully immunocompetent. In order to evaluate the neonatal immune system status and investigate the reasons for increased neonatal susceptibility to infections, the major lymphocytes subpopulations were studied in newborns comparing the results to adult controls. The cord blood from 21 term-newborns and the peripheral blood from 23 adults were analyzed using fluorochrome labelled monoclonal antibodies and two-color flow cytometry. The percentage of T lymphocytes was lower in newborns (64.9 versus 72.8% in adults), as well as the percentage of NK cells (4.8 versus 15.5%). On the contrary, the proportions of unlabelled cells were increased in term cord blood. The percentage of cytotoxic T lymphocytes was significantly lower in term-newborns as compared to the adult controls (17.8 versus 30.3%), and so were the percentages of activated T lymphocytes (0.3 versus 3.7%) and cytotoxic non-MHC restricted T lymphocytes (0.2 versus 1.8%). The expression of CD45R0 marker on neonatal lymphocytes was very low (1%). These characteristics of newborn lymphocytes phenotype are the result of inexperienced and partly undeveloped immune system.

Flow-cytometric lymphocyte phenotyping using automated SimulSET Software gating procedure.

The peripheral blood lymphocyte phenotypes of 20 healthy young normal subjects between the ages 21 and 29 were determined by dual fluorescence analysis with fluorochrome--labeled monoclonal antibodies (mAbs). Samples were prepared by a whole blood lysis technique and analysed on a FACScan flow cytometer using SimulSET Software. Values for lymphocyte subpopulations (percentage and absolute count) are presented. Some values are different in relation to sex. The most important steps in SimulSET software gating procedure of lymphocytes are also described.