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

Abstract

BackgroundWhile 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.MethodsIn 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.ResultsAn 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.ConclusionsThese 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.

Cell-intrinsic regulation of peripheral memory-phenotype T cell frequencies

“…On the other hand, siblings were far similar to each other in memory subset frequencies than non-siblings were, suggesting a hereditary component or shared environmental factors in regulating memory lymphocyte frequencies. Any similarity between siblings could be attributed to early life influences, since it is well recognized that both intra-uterine [49,50] and neonatal [51] stress impacts immune system development, and a recent study [13] has shown a prominent role for co-habitation in determining immune phenotypes. Our findings are consistent with two previous studies [1,14] which report high degree of heritability for majority of immune subsets.…”

Absence of Nonclassical Monocytes in Hemolytic Patients: Free Hb and NO-Mediated Mechanism

“…In healthy adult individuals, the frequency of classical monocytes varies from 80 to 90% of total monocytes. On the other hand, nonclassical monocytes constitute about 8-10%, whereas neonates have a low number of nonclassical monocytes [8, 9]. The phenotype and function of monocyte subsets change extensively in inflammatory disease conditions.…”

Birth Weight and the Development of Functional Gastrointestinal Disorders in Infants

“…In accordance with this hypothesis, an increased risk of infections and aberrant immune development has been reported in both preterm [ 14 26 ] and SGA infants [ 27 28 29 30 ].…”