title: Changes in plasma FcRIII demonstrate increasing receptor production during late pregnancy and after preterm birth.
abstract: We have previously described reduced expression of the Fc gamma receptor type III on the cell membrane (M-FcRIII) of neutrophils from very preterm neonates. To investigate the mechanism underlying this reduced receptor expression, we have measured neutrophil-derived soluble FcRIII (S-FcRIII) in the plasma of fetuses and neonates from 19 wk gestation. S-FcRIII in fetal plasma and in preterm neonates born before 32 wk gestation was consistently low [mean 13.6 +/- 1.2% (mean adult S-FcRIII = 100%, range 30-240%)]. In utero, S-FcRIII starts to rise from 33 wk and increases more than 4-fold to reach adult levels by term. S-FcRIII measured sequentially in preterm infants born as early as 24 wk of gestation showed a rapid postnatal increase to reach adult levels within 3 wk of birth. The changes in S-FcRIII paralleled changes in M-FcRIII expression on the cell surface. These observations point to a reduced rate of FcRIII production by fetal neutrophils as opposed to an increase in receptor release. The parallel increase in S-FcRIII and M-FcRIII suggests that there may be a programmed activation of FcRIII synthesis within individual cells late in the 3rd trimester of fetal development. In addition, FcRIII production may be switched on early by preterm birth.
authors: University Department of Haematology, Royal Liverpool Hospital, United Kingdom.
authors: R
authors: R
authors: Carr
authors: T W
authors: TW
authors: Huizinga
authors: M
authors: M
authors: Kleijer
authors: J M
authors: JM
authors: Davies
mesh_terms: D002462:Cell Membrane / Q000276:immunology; D005260:Female; D005312:Fetal Blood / Q000276:immunology; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000276:immunology*; D009504:Neutrophils / Q000276:immunology*; D011247:Pregnancy; D017452:Receptors, IgG / Q000096:biosynthesis / Q000378:metabolism*; D012995:Solubility
chemical_list: D017452:Receptors, IgG