title: IgG placental transfer in healthy and pathological pregnancies.
abstract: Placental transfer of maternal IgG antibodies to the fetus is an important mechanism that provides protection to the infant while his/her humoral response is inefficient. IgG is the only antibody class that significantly crosses the human placenta. This crossing is mediated by FcRn expressed on syncytiotrophoblast cells. There is evidence that IgG transfer depends on the following: (i) maternal levels of total IgG and specific antibodies, (ii) gestational age, (iii) placental integrity, (iv) IgG subclass, and (v) nature of antigen, being more intense for thymus-dependent ones. These features represent the basis for maternal immunization strategies aimed at protecting newborns against neonatal and infantile infectious diseases. In some situations, such as mothers with primary immunodeficiencies, exogenous IgG acquired by intravenous immunoglobulin therapy crosses the placenta in similar patterns to endogenous immunoglobulins and may also protect the offspring from infections in early life. Inversely, harmful autoantibodies may cross the placenta and cause transitory autoimmune disease in the neonate.
authors.affiliation: Departamento de Pediatria, Faculdade de Medicina, Universidade de São Paulo, Av. Dr. Enéas Carvalho de Aguiar, 647, Cerqueira César, São Paulo, SP 05403-900, Brazil. patpalm@usp.br
authors.forename: Patricia
authors.initials: P
authors.lastname: Palmeira
authors.forename: Camila
authors.initials: C
authors.lastname: Quinello
authors.forename: Ana Lúcia
authors.initials: AL
authors.lastname: Silveira-Lessa
authors.forename: Cláudia Augusta
authors.initials: CA
authors.lastname: Zago
authors.forename: Magda
authors.initials: M
authors.lastname: Carneiro-Sampaio
mesh_terms: D005260:Female; D006801:Humans; D007112:Immunity, Maternally-Acquired / Q000276:immunology*; D007074:Immunoglobulin G / Q000276:immunology* / Q000378:metabolism / Q000627:therapeutic use; D007153:Immunologic Deficiency Syndromes / Q000276:immunology* / Q000517:prevention & control; D007231:Infant, Newborn; D018448:Models, Immunological; D010920:Placenta / Q000276:immunology* / Q000378:metabolism; D011247:Pregnancy; D011248:Pregnancy Complications
chemical_list: D007074:Immunoglobulin G