Which antibody type is involved in the attack on fetal red blood cells during Rh alloimmunization?

The involvement of IgG antibodies in the attack on fetal red blood cells during Rh alloimmunization is critical to understanding this immune response. When an Rh-negative mother is exposed to Rh-positive fetal blood cells, typically during delivery or some form of bleeding, her immune system may recognize the Rh factor as foreign. This triggers the production of IgG antibodies against the Rh antigen.

IgG is capable of crossing the placenta, which allows these antibodies to travel to the fetus. Once in the fetal circulation, these maternal IgG antibodies can bind to the fetal Rh-positive red blood cells, leading to hemolysis, or destruction of these cells. This process results in conditions such as hemolytic disease of the newborn (HDN), highlighting the significant role that IgG antibodies play in this specific immunological scenario.

In contrast, other antibody types such as IgA, IgE, and IgM do not play a similar role in this context. IgA is primarily found in mucosal areas and bodily secretions; IgE is involved in allergic responses and protection against parasitic infections; while IgM is typically the first antibody produced in response to an infection and does not cross the placenta efficiently. Therefore, the unique characteristics of IgG, particularly its