Pediatric Concentrations of S100B Protein in Blood: Age- and Sex-related Changes

Abstract

The term S100 refers to members of a multigenic family of calcium-modulated proteins, mostly of low molecular mass (∼10 000 Da), first identified as a protein fraction detectable in the brain and called S100 because of its solubility in a solution of 100 g/L ammonium sulfate (1). The protein seems to be most abundant in glial cells, although its presence in neuronal subpopulations has also been reported (2)(3). The biological role of this protein within the cell populations that contain it has not been completely elucidated. The possibility of an extracellular biological role for S100B, which, secreted by astrocytes as a cytokine, may have a neurotrophic effect during both development and nerve regeneration at physiologic (nmol/L) concentrations, appears particularly interesting (4)(5)(6)(7). Recent studies conducted in perinatal medicine that showed a correlation between S100B protein measured in several biological fluids (i.e., amniotic fluid, cord blood, and urine) and gestational age (8)(9)(10) appear consistent with a neurotrophic role for the protein. The present study offers a reference curve for S100B protein in peripheral blood from the postnatal period to 15 years of age in healthy pediatric patients. Between April 1997 and July 2000, we routinely collected blood samples for S100B measurement from healthy children admitted to our Institute for routine day-hospital investigations. All of the children were delivered at term without perinatal complications, and their clinical history, from birth to the time of blood sampling, was negative for neurologic abnormalities and comorbidities. We recruited a total of 1004 healthy children (males, n = 482; females, n = 522) whose ages ranged from 1 month to 15 years of age (mean, 8 years). On admission to the study, all of the patients were checked against routine clinical and laboratory indices, …