Immunohematologic aspects of alloimmunization and alloantibody detection: A focus on pregnancy and hemolytic disease of the fetus and newborn

Hemolytic Disease of the Newborn: A Review of Current Trends and Prospects

“…Suppose the baby's blood crosses over and reaches the mother's incompatible RBCs; the mother's immune system perceives the fetal antigens as non-self and fights them by releasing antibodies that do not hesitate to attack and destroy them. 2 Usually, the crossover occurs through the placenta during pregnancy or delivery. This leads to severe complications in the baby's system, which may even lead to the ultimate demise of the baby.…”

“…Usually, when the first child inherits paternal D antigen, whose inheritance has been shown to follow an autosomal dominant pattern, and there occurs an event that leads to mixing of maternal and fetal blood, the mother starts producing anti-D antibodies through a process referred to as alloimmunization, as she lacks the D antigen. 2 Immunologically, antibody secretion initially starts with IgM, which cannot cross the placental barrier, but is then followed by isotype switching, which produces IgG antibodies. IgG antibodies can cross the placental barrier, and they do so during the second and or subsequent pregnancies, attacking the fetal RBCs and causing hemolysis and associated complications such as Hydrops fetalis and jaundice.…”

“…Maternal antibodies reach the fetus when IgG antibodies, following antibody isotype switching, cross the placenta and enter the fetal circulation or through FMH. 2,8 A 2017 review by Ree et al stated a global shift in HDN from 1% with a death rate of 50% before introducing Rh-immunoprophylaxis in 1968 to 0.5% after its introduction. The incidences decreased further to 0.1% with the introduction of antepartum Rh D immunoprophylaxis in 1970.…”

“…IgM-type antibodies are the first to form due to FMH, and because they cannot cross the placenta, the first pregnancy survives, leaving behind an already sensitized immune system. 2 In the event of rhesus factor incompatibility, the fetus is at risk. At a later stage, in subsequent pregnancies, the mother's rhesus antibodies may attack the fetus's antigens, resulting in alloimmune hemolysis in the fetus.…”

Noninvasive diagnostics of fetal KEL*01.01 allele from maternal plasma of immunized women using digital PCR protocols

“…Immunized pregnant women who have identified anti-K antibodies against the K antigen from the Kell blood group system (ISBT 006) are in danger of having the fetus and newborn being affected by a hemolytic disease of the fetus and newborn [HDFN]. 1 However, if the father of the fetus is heterozygous (K/k), the child has a chance of inheriting the blood group allele compatible to the maternal allele and not being at risk of the disease. Thus, early prediction of fetal K status may help to plan personal management of a pregnancy.…”