Comparison of Human Neonatal and Adult Blood Leukocyte Subset Composition Phenotypes.

The human peripheral leukocyte subset composition depends on genotype variation and pre-natal and post-natal environmental influence diversity. We quantified this composition in adults and neonates, and compared the median values and dispersal ranges of various subsets in them. We confirmed higher frequencies of monocytes and regulatory T cells (Tregs), similar frequencies of neutrophils, and lower frequencies of CD8 T cells, NKT cells, B1 B cells and gamma-delta T cells in neonatal umbilical cord blood. Unlike previous reports, we found higher frequencies of eosinophils and B cells, higher CD4:CD8 ratios, lower frequencies of T cells and iNKT cells, and similar frequencies of CD4 T cells and NK cells in neonates. We characterized monocyte subsets and dendritic cell (DC) subsets in far greater detail than previously reported, using recently described surface markers and gating strategies and observed that neonates had lower frequencies of patrolling monocytes and lower myeloid dendritic cell (mDC):plasmacytoid DC (pDC) ratios. Our data contribute to South Asian reference values for these parameters. We found that dispersal ranges differ between different leukocyte subsets, suggesting differential determination of variation. Further, some subsets were more dispersed in adults than in neonates suggesting influences of postnatal sources of variation, while some show the opposite pattern suggesting influences of developmental process variation. Together, these data and analyses provide interesting biological possibilities for future exploration

Underweight Full-Term Indian Neonates Show Differences in Umbilical Cord Blood Leukocyte Phenotype: A Cross-Sectional Study

<div><p>Background</p><p>While infections are a major cause of neonatal mortality in India even in full-term neonates, this is an especial problem in the large proportion (~20%) of neonates born underweight (or small-for-gestational-age; SGA). One potential contributory factor for this susceptibility is the possibility that immune system maturation may be affected along with intrauterine growth retardation.</p><p>Methods</p><p>In order to examine the possibility that differences in immune status may underlie the susceptibility of SGA neonates to infections, we enumerated the frequencies and concentrations of 22 leukocyte subset populations as well as IgM and IgA levels in umbilical cord blood from full-term SGA neonates and compared them with values from normal-weight (or appropriate-for-gestational-age; AGA) full-term neonates. We eliminated most SGA-associated risk factors in the exclusion criteria so as to ensure that AGA-SGA differences, if any, would be more likely to be associated with the underweight status itself.</p><p>Results</p><p>An analysis of 502 such samples, including 50 from SGA neonates, showed that SGA neonates have significantly fewer plasmacytoid dendritic cells (pDCs), a higher myeloid DC (mDC) to pDC ratio, more natural killer (NK) cells, and higher IgM levels in cord blood in comparison with AGA neonates. Other differences were also observed such as tendencies to lower CD4:CD8 ratios and greater prominence of inflammatory monocytes, mDCs and neutrophils, but while some of them had substantial differences, they did not quite reach the standard level of statistical significance.</p><p>Conclusions</p><p>These differences in cellular lineages of the immune system possibly reflect stress responses in utero associated with growth restriction. Increased susceptibility to infections may thus be linked to complex immune system dysregulation rather than simply retarded immune system maturation.</p></div

Characteristics of Adult volunteers.

<p>Characteristics of Adult volunteers.</p

absolute counts of cell subsets.

<p>absolute counts of cell subsets.</p

Characteristics of participant population- cord blood.

<p>Characteristics of participant population- cord blood.</p

Median-corrected variances and p-values (Brown-Forsythe test) of leukocyte subsets in AB and CB.

<p>Median-corrected variances and p-values (Brown-Forsythe test) of leukocyte subsets in AB and CB.</p

Frequencies and concentrations (cells/μl of blood) of major leukocyte subsets in AB versus CB.

<p>Numbers in the plots indicate p-values.</p

Variances in AB and CB in various leukocyte lineages.

<p>Values on y-axis are median-corrected variances. Asterices mark p<0.05 (Brown-Forsythe test).</p

Frequencies of AB and CB subsets.

<p>Frequencies of AB and CB subsets.</p

NK cells, but not innate-like T cells, show significant difference between AGA and SGA cord blood.

<p>(A) Comparison of proportions and absolute concentrations of NKT, iNKT and TCRγ/δ cells (median, IQR and 95% CI) along with p values. (B) Comparison of proportions and absolute numbers of immature NK cells (median, IQR and 95% CI) along with p values.</p