Neonatal Blood Cells Research Articles

A novel subpopulation of CD45RA+ CD4+ T cells expressing IL-2 receptor α-chain (CD25) and having a functionally transitional nature into memory cells

Differential expression of various isoforms of leukocyte common antigen (CD45), which arises from alternate mRNA splicing, identifies naive and memory populations of human T cells. Some memory (CD45RO+ CD45RA-) populations of CD4+ T cells from adult individuals express IL-2 receptor (IL-2R) alpha-chain (CD25), but naive (CD45RO- CD45RA+) CD4+ T cells only do so to a small degree. We found that a small but significant fraction of CD4+ T cells in neonatal blood expressed CD25, although most generally exhibited the phenotype of naive cells. It was demonstrated that purified neonatal CD25+ CD4+ T cells expressed mRNA for the IL-2R alpha-chain. Two-color immunofluorescence analysis disclosed that a CD25+ population of neonatal CD4+ T cells had the naive (CD45RA+ CD45RO-) phenotypes. These CD25+ CD4+ T cells from newborns could express mRNA for some specified lymphokines such as IL-4, IL-5, and interferon-gamma on activation in a similar manner to CD45RO+ (memory) CD4+ T cells from adults. Notably, polymerase chain reaction analysis demonstrated that neonatal CD45RA+ CD4+ T cells expressing CD25 contained spliced mRNA transcripts possibly encoding CD45RO in addition to CD45RA-associated transcripts, seemingly indicating that this population might be in the recently antigen-primed states. Such a small population of CD45RA+ CD4+ T cells expressing CD25 appeared to be present in the blood throughout human life. The results suggest that CD4+ T cells with the naive (CD45RA+) phenotype expressing IL-2R alpha-chain (CD25) represent the novel transitional population in the maturation process of naive into memory CD4+ T cells.

The presence of free D-aspartic acid in rodents and man

Free D-aspartic acid is present in appreciable quantities in the brain and other tissues of rodents and in human blood. In the newborn rat, the highest concentration of D-aspartic acid was found in cerebral hemispheres, where, at 164 nmol/g (8.4% of the total aspartic acid), the level of D-aspartic acid exceeds that of many essential L-amino acids. The highest ratio of D- to total aspartic acid (38%) occurred in neonatal blood cells. In the adult rat, the highest concentration was present in the pituitary gland (127 nmol/g, 3.8%). Within the central nervous system marked regional differences are present and characteristic changes with development take place. In general, the levels of D-aspartic acid fall rapidly with increasing age. In cerebral hemispheres adult values (13 nmol/g, 0.43%) are approached within one week. D-aspartic acid concentrations may also be higher in young humans since fetal blood, taken from placental cord, contains 2.6 nmol/g (4.9%) of D-aspartic acid, a value five times that of adult human blood. These distributional patterns and developmental changes may be the result of differences in the ability of various tissues to dispose of an extraneous metabolite, or, reflect alterations in a specific functional requirement for D-aspartic acid.

Volumetric erythrocyte macrocytosis induced by hydroxyurea.

An atypical form of macrocytosis termed volumetric macrocytosis is described. In contrast to the macrocyte associated with megaloblastic anemia and the pseudomacrocyte caused by viscoelastic defects, the volumetric macrocyte is characterized by an increased mean corpuscular volume and a normal cell diameter. The volumetric macrocyte proves to be thicker than the normocytic red blood cell. This large erythrocyte is overhydrated and contains an increased quantity of hemoglobin. The cell has many characteristics in common with the red blood cells of neonates. Volumetric macrocytosis accompanies sustained hydroxyurea therapy and may represent a drug-induced dyserythropoiesis.

Neonatal blood cell count in health and disease. II. Values for lymphocytes, monocytes, and eosinophils

The distribution of normal cell counts (the reference range) has been determined previously for circulating neutrophils in infants from birth to 28 days of age. We have determined the reference ranges for the absolute peripheral blood lymphocyte, monocyte, and eosinophil counts obtained from 393 infants in this same cohort. Furthermore, white blood cell counts were obtained from three groups of infants with perinatal complications previously shown to be associated with abnormal neutrophil values (ABO incompatibility, n = 82; maternal hypertension, n = 68; neonatal sepsis, n = 140) and compared with the derived reference ranges; significant alterations in the distribution of cell counts were found in each of these groups at different times. Our data provide reference ranges for lymphocyte, monocyte, and eosinophil counts in the neonatal period and evidence of the effect of specific perinatal events on these cell counts.

Differentiation of human erythroid cells is associated with increased O-glycosylation of the major sialoglycoprotein, glycophorin A.

Glycophorin A, the major human erythrocyte sialoglycoprotein, is found exclusively on cells of the erythroid lineage. The amino acid sequence is known, and glycophorin A isolated from mature erythrocytes contains a single N-glycosidic and 15 O-glycosidic oligosaccharides. Monoclonal antibodies against erythrocyte glycophorin A reacted weakly with erythroid precursors while a monospecific rabbit antiserum reacted strongly with immature and mature red cells. Glycophorin A was isolated from cells representing various stages of erythropoiesis in normal bone marrow, from blood cells of neonates with erythroblastosis fetalis, and from the erythroleukemic cell lines K562 and HEL before and after induced differentiation. Analysis of the oligosaccharides showed less O-glycosylation of glycophorin A in erythroid precursors. The degree of glycosylation increased concomitantly with differentiation.

Domains of receptor mobility and endocytosis in the membranes of neonatal human erythrocytes in the membranes of neonatal human erythrocytes and reticulocytes are deficient in spectrin

It has previously shown (Schekman, R., and S.J. Singer, Proc. Natl. Acad. Sci. U.S.A. 73:4075-4079) that receptors in the membranes of neonatal human erythrocytes show a restricted degree of lateral mobility, whereas in adult human erythrocytes the receptors are essentially immobile. This restricted mobility is exhibited, for example, when concanavalin A (Con A) induces a limited clustering of its receptors in the neonatal erythrocyte membrane, resulting in the formation of invaginations and endocytic vesicles. This does not happen with adult cells. By the use of indirect immunoferritin labeling of ultrathin frozen sections of Con A-treated neonatal blood cells, we now show that the invaginations and endocytotic vesicles do not stain for spectrin, whereas the adjacent unperturbed membrane is heavily stained. The reticulocytes in the neonatal cell population undergo substantially more Con A-induced invagination and endocytosis than do the erythrocytes. These results lend strong support to the hypothesis that specialized discrete domains exist, or are induced, in the membranes of these neonatal cells, in which receptors are laterally mobile, whereas in the remaining (and predominant) part of the membrane the receptors are immobile. Such mobile domains are characterized by an absence of spectrin. During the maturation of the neonatal reticulocyte to erythrocyte, it is proposed that these domains are in large part, but not completely, eliminated.

Scanning electron microscopy of human reproductive physiology.

Recent findings on the scanning electron microscopical (SEM) structures of epithelium of female and male reproductive organs spermatozoa placenta amniotic cells umbilical cord neonatal blood cells and pathologies of their structures - carcinoma of the endometrium cervix vagina and vulva - are reviewed. The methodology in preparation of soft tissue cervical mucus and amniotic tissues is described including pinning fixation dehydration and drying mounting and metal coating and viewing with the SEM. There are striking morphological differences between the tissue organization of the mucosa of different segments of the reproductive tract. These morphological di fferences are discussed in terms of observed physiological functions. SEM is a useful tool in studying infertility the status of the newborn monitoring fetal maturity and carcinoma diagnosis.

Radiometric Detection of Bacteremia in Neonates

The predicted prevalence of false positive blood cultures due to hyperactive neonatal blood cells in a radiometric detection system was confirmed. Suppression of this blood background radioactivity in the system was achieved by using a hypertonic medium containing 10% sucrose. The radiometric system produced accurate results as fast as the conventional blood culturing method, saved labor and minimized the recovery of extraneous contaminants.

Nucleoside phosphatases of fetal and maternal blood cells: electron microscope study.

Surface membranes of the blood cells located within the maternal blood sinuses of the rat placenta contain reaction products of nucleoside phosphatases. Fetal blood cells separated from maternal blood by the placental labyrinth show no activity during normal or prolonged gestation. Neonatal blood cells examined 34 hours after parturition show these enzyme activities.