Alterations in lymphocyte phenotype of infected preterm newborns.

The cord blood lymphocytes from 44 premature newborns were analyzed using two-color monoclonal antibodies and flow cytometry. Depending on whether or not there was an infection at birth, the newborns were divided into two groups and the immunophenotypes of infected and uninfected newborns were compared. The percentage of T lymphocytes (CD3+) was significantly lower in the infected prematures. The percentage of both helper and cytotoxic T lymphocytes was lower. The proportion of activated T lymphocytes, cytotoxic non-MHC-restricted T lymphocytes, NK cells and B lymphocytes did not differ between the group of infected and the group of uninfected prematures. The percentage of memory helper T lymphocytes (CD45RO+CD4+) was very low in premature newborns regardless of whether or not they were infected and could not be used as a marker of bacterial infection at this age.

Antenatal predictors of the neurologic sequelae at 3 years of age: a multivariate analysis.

OBJECTIVE: To study the association between fetal blood flow abnormalities and the occurrence of long-term neurologic sequelae. STUDY DESIGN: Umbilical, aortic and middle cerebral artery blood flow parameters were obtained by Doppler examination and retrospectively analyzed in 128 high-risk singleton pregnancies, followed by neurologic examination of the surviving children at 3 years of age. Traditional parameters of neurologic outcome (Apgar scores, intrauterine growth retardation (IUGR), umbilical artery pH and base deficit, gestational age, birth weight, newborn encephalopathy, mode of delivery, fetal heart rate, neurosonographic examination) were included as possible confounding factors. Mann-Whitney U-test, Student's t-test, analysis of variance or Fisher's exact test, where applicable, were used for the univariate analysis. A stepwise logistic regression procedure was conducted to test the independent association of selected perinatal risk factors on neurological outcome. Statistical significance was assumed at P<0.05. RESULTS: Eighteen out of 114 surviving children suffered neurologic illness at 3 years of age. Four children had major neurologic dysfunction and the remaining 14 suffered minor or mild form of the disease. Although blood flow parameters and various perinatal parameters did not differ significantly between the group of children with major neurologic dysfunction and healthy children, aortic resistance index showed an independent association with occurrence of minor or mild neurologic disabilities. CONCLUSION: Antenatal evaluation of the aortic blood flow might be an important predictive variable for permanent neurologic disturbances.

Two-color flow cytometric analysis of preterm and term newborn lymphocytes.

Immune system maturation proceeds postnatally in humans. Therefore, newborns, especially those of a lower gestational age, are not fully immunocompetent and are more likely to acquire perinatal infections. In order to investigate the neonatal immune system status, the major lymphocyte subpopulations were studied in newborns of different gestational age, comparing term newborns and adults. The cord blood from 66 newborns and the peripheral blood from 23 adults were analyzed using fluorochrome labelled monoclonal antibodies and two-color flow cytometry. The newborns were divided into three groups according to their gestational age. Ten prematures were under 32 weeks of gestation, 35 were of 32-37 weeks and there were 21 term newborns. The percentage of cytotoxic T lymphocytes (CD4 CD8+) was lower in term newborns as compared to the adult controls (17.8 versus 30.3%), and so were the percentages of activated T lymphocytes (CD3+Ia+; 0.3 versus 3.7%), cytotoxic non-MHC restricted T lymphocytes (CD3+CD16+CD56+; 0.2 versus 1.8%) and NK cells (CD3-CD16+CD56+; 4.8 versus 15.5%). On the contrary, the proportions of unlabelled cells were increased in term cord blood. The expression of CD45R0 marker on neonatal lymphocytes was very low (1%). In comparison to the higher-gestation newborns, the lower gestation prematures had reduced percentages of T lymphocytes (CD3+; 43 versus 65%), mostly helper T lymphocytes (CD4+CD8-; 35 versus 50%), and increased percentages of unlabelled cells. The percentages of NK cells (CD3+CD16+CD56+) and B lymphocytes (CD3-CD19+; CD3-Ia+) did not differ among the tested newborn groups. There were no significant differences in major lymphocyte subpopulations between the group of highest-gestation prematures and the group of term newborns that differed significantly when compared to adults. The lowest-gestation newborns showed the most immature lymphocyte phenotype with the highest percentages of unlabelled cells.

[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.

Cytotoxic T-cell response to H-Y antigen by B6.C-H-2bm12 and B10.BR mice.

Cytotoxic T-cell response to the male-specific histocompatibility antigen (H-Y) is often used as an experimental model for studying the genetic control of the immune response. This anti-H-Y response is shown to be a complex one, with multicellular interactions involving genes of the H-2 complex, and also some genes unlinked to H-2. For the analysis of the genetic control of the anti-H-Y immune response, different inbred strains have been used and classified accordingly as responders or non-responders. During the authors' studies of the genetic control of the immune response, some of the strains described as non-responders were found to behave as responders, namely strains B6.C-H-2bm12 and B10.BR. This finding has added to the intricacy of current data on the genetic control of immune response to H-Y antigen.

Helper effects required during in vivo priming for a cytolytic response to the H-Y antigen in nonresponder mice.

Induction of H-Y-specific cytotoxic T lymphocyte (CTL) responses in nonresponder female mice was attempted by i.v. injection of allogeneic male cells, followed by in vitro restimulation of recipient spleen cells with syngeneic male cells. Responses were obtained only in two strain combinations in which the recipients, although phenotypically nonresponders, carried responder alleles at class I major histocompatibility complex (MHC) loci, and the immunizing cells differed from the recipients at class II MHC loci. The two positive strain combinations were B10.A(2R) anti-B10.A(4R), and B10.GD anti-B10.D2(R101). In the first combination, both recipient and donor are nonresponders to H-Y, and the CTL are induced via a bystander effect of another CTL response to a previously undetected minor histocompatibility (H) antigen. This "carrier" antigen can only induce CTL against H-Y and itself when the immunizing cells express class II MHC molecules. Furthermore, the presence of H-Y and the carrier antigen on the same cell is a prerequisite for the generation of H-Y-specific CTL. In the second combination, the recipient is a nonresponder, whereas the donor is a responder. The two strains differ at only E alpha and E beta class II MHC loci. For the induction of CTL, H-Y and the foreign E molecule must be expressed on the same cells. Thus, the B10.D2(R101) cells that express E molecules on their surface probably provide the E-nonexpressor B10.GD recipients with a stimulus for the generation of H-Y-specific T helper cells. The data are consistent with the notion that antigen-specific class II MHC-restricted T helper cells are involved in the initiation of CTL responses to minor H antigens.