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Maternal-fetal immunoglobulin transport: Studies on the binding, internalization, and release of IgG by chick yolk sac tissue and cultured cells

Thesis/Dissertation ·
OSTI ID:5479088
Immunoglobulin G (IgG) is transported from the yolk across the endodermal cells of the yolk sac and into the fetal circulation during chick embryonic development, thus providing the chick with passive immunity until it becomes immunocompetent. Saturable, Fc-specific receptors are present on the endodermal cells and are believed to mediate this transfer. In this study, IgG receptors were shown to be present on the yolk sac endodermal cells throughout the 21 days of development, although most of the transport occurs during the last 3 days prior to hatching. Fluorescently conjugated IgG was internalized by a receptor mechanism into small apical vesicles in yolk sac endoderm throughout, but cells from 19 day yolk sacs internalized more conjugate than those from 14 day yolk sacs. This was confirmed and quantitated by assaying the internalization of {sup 125}I-IgG into yolk sac tissue. IgG was internalized by a receptor mediated mechanism, reaching a steady state level after 1 to 2 hours. Although both ages of yolk sac tissue possessed the same number of surface IgG receptors, as measured by equilibrium binding assays at 4{degree}C, 19 day yolk sac had the capacity to internalize six times as much IgG by a receptor mechanism as 14 day yolk sac.
Research Organization:
Maryland Univ., Baltimore, MD (USA)
OSTI ID:
5479088
Country of Publication:
United States
Language:
English