Rh Factor in Humans

Rh factor

Rh factor is an RBC antigen that can trigger haemolytic disease in newborns due to incompatibility between maternal and infant blood factors

Explain inheritance of Rh factor

A person inheriting at least one Rh gene will be Rh positive; only those persons inheriting two recessive genes are Rh negative.

Rabbits

________ inoculated with the RBCs of rhesus monkeys produced an antibody that also reacted with human RBCs.

How is Rh factor indicated?

This factor is denoted as ‘Rh+’ or ‘Rh-”

When does placental sensitization occur?

The potential for placental sensitization occurs when a mother is Rh negative and her unborn child is Rh positive.

Erythroblastosis foetalis

The fetus is at risk when the maternal anti-Rh antibodies cross the placenta into the fetal circulation, where they affix to fetal RBCs and cause complement-mediated lysis

Symptoms of erythroblastosis foetalis

Destruction of RBC in new born, severe anemia, jaundice, and enlarged spleen. and liver.

What type of antibody is produced in maternal blood against Rh factor of the foetus?

IgG antibody

Antibody that can cross placental barrier

IgG antibody

How can erythroblastosis foetalis be prevented?

If there is any possibility that the fetus is Rh, the mother must be passively immunized with antiserum containing antibodies against the Rh factor (Rho [D] immune globulin, or RhoGAM*)

When is the antiserum injected?

The antiserum is injected at 28 to 32 weeks and again immediately after delivery