IgG receptors on the embryonic chick yolk sac.

R L Tressler,T F Roth

doi:10.1016/s0021-9258(18)47740-x

R L Tressler, T F Roth

Open Access

https://doi.org/10.1016/s0021-9258(18)47740-x

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Abstract

Survival of the chick depends upon the transfer of maternal IgG from the egg yolk into the fetal circulation. Radiolabeled chicken IgG binds specifically to both fixed and unfixed yolk sac tissue from day 7 or 8 of embryogenesis through at least day 18. This binding is saturable, Fc-specific, pH-dependent, and reversible. Chicken Fc fragments and some heterologous IgGs compete with IgG binding, whereas bovine serum albumin, phosvitin, conalbumin, chicken IgM, and chicken Fab fragments do not. Eight-day embryos appear to have only a low affinity receptor, KD = 3.4 x 10(-7) M, but 18-day embryos have an additional high affinity receptor, KD = 3.0 x 10(-8) M. The membrane density of the low affinity receptor remains essentially constant throughout development.

Highlights

Survival of the chick depends upon the transfer of maternal IgG from the egg yolk into the fetal circulation
IgG receptors on the oocyte bind and move all subclasses of hen serum IgG into the egg (Loeken and Roth, 1983).' These receptors and those on 7- to 18-day yolk sac share a pH optimum of 6.0-6.3 (Linden and Roth, 1978).' BSA2and ovalbumin do not displace bound lZ5I-IgG,but bovine yglobulin does
Globulin-free BSA, salt-free goat IgG, salt-free bovine IgG, phosvitin, conalbumin, mecuripapain, and lipopolysaccharide from Salmonella enteritis were obtained from Sigma

Summary

IgG Receptors on the Embryonic Chick Yolk Sac*

Radiolabeled chicken IgG binds to both fixed and unfixed yolk sac tissue from day 7 or 8 of embryogenesis through at least day 18. This binding is saturable, Fc-specific, pH-dependent, and reversible. Eight-day embryos appear to have only a low affinity receptor, KO = 3.4 x. In this paper we report the properties of the IgG receptor on the fetal chick yolk sac and demonstrate the saturability, specificity, and reversibility of ligand binding as well as itsexpression at early and late developmental stages

EXPERIMENTAL PROCEDURES

RESULTS

Chick IgG Fc Yolk Sac Receptor

Competition of Chicken Fc andFabFragments for IgG

DISCUSSION

Weight of yolk