Abstract
Maternal passage of immunoglobulin G (IgG) is an important passive mechanism for protecting the infant while the neonatal immune system is still immature and ineffective. IgG is the only antibody class capable of crossing the histological layers of the placenta by attaching to the neonatal Fc receptor expressed at the level of syncytiotrophoblasts, and it offers protection against neonatal infectious pathogens. In pregnant women with autoimmune or alloimmune disorders, or in those requiring certain types of biological therapy, transplacental passage of abnormal antibodies may cause fetal or neonatal harm. In this review, we will discuss the physiological mechanisms and benefits of transplacental transfer of maternal antibodies as well as pathological maternal situations where this system is hijacked, potentially leading to adverse neonatal outcomes.
Highlights
Immunological adaptative changes occurring during pregnancy allow maternal tolerance towards the fetus and placenta, which practically constitute semi-allografts as 50% of their antigens have a paternal provenience [1]
In a small cohort of six infants born to mothers with COVID-19 infection, Immunoglobulin G (IgG) was present in all cases and the neonatal level was well correlated with maternal immunoglobulin levels
Neonates born to mothers who are known before conception to have autoimmune blistering diseases such as pemphigus vulgaris (PV), pemphigus foliaceus (PF), bullous pemphigoid (BP), linear Immunoglobulin A bullous dermatosis (LABD) or epidermolysis bullosa
Summary
Immunological adaptative changes occurring during pregnancy allow maternal tolerance towards the fetus and placenta, which practically constitute semi-allografts as 50% of their antigens have a paternal provenience [1]. Besides gestational age as an important factor in the transfer of antibodies, the process is influenced by several aspects such as maternal immunocompetence, concomitant infections, specific antibody levels acquired postimmunization, placental integrity, class of IgG and type of antigen [7]. These variables represent the basis for strategies regarding maternal immunization, aiming to protect newborns against infectious diseases, and for the development of special surveillance protocols in situations such as maternal autoimmune or alloimmune conditions where harmful antibodies transferred across the placenta may cause severe fetal complications
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