Hungarian Immunology

[Transmission of antibodies from mother to offspring: evolutionary aspects]

BAINTNER Károly

OCTOBER 10, 2005

Hungarian Immunology - 2005;4(03-04)

[The earliest known form of transmission of antibody is the transport from the maternal circulation into the yolk during vitellogenesis (in birds and reptiles), followed by endodermal uptake and transport into the embryonal circulation. During the early mammalian evolution lacteal secretion and the development of the placenta opened new ways to feed the young. These changes also resulted in alterations in sites and mechanisms of transmission of immunoglobulins. In a few species (e.g. rabbit and rodents) the yolk-less yolk sac gained a new function, i.e. the absorption of uterine secretion. In most of the mammalian species the neonatal type Fc-receptor (FcRn) plays a key role in the transmission and confers IgG-selectivity on the process. In ungulates undigested colostral proteins, including antibodies, are absorbed non-selectively by the gut, mediated by sizable transport vacuoles. The limited postnatal transmission period (24 to 48 h) is compensated by the considerable length of the small intestine and the efficiency of absorption. In the human chorioallantoic placenta the two steps of transmission (maternal secretion and absorption by the offspring) were reduced to a single step. Absorption of IgG is often carried out in a proteolytic environment (yolk sac, gut lumen, intestinal vacuoles), and as a result, different mechanisms evolved for the protection of antibody.]

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