Rhesus system of blood typing

The major difference between the the O-A-B system & the Rh system is that in the O-A-B system, the agglutinins responsible for causing transfusion reactions develop spontaneously, while in the Rh system spontaneous agglutinins almost never occur.
An individual must be exposed to large amounts of transfused blood containing Rh antigen before enough agglutinins to cause significant transfusion reaction are developed.
Are 6 common types of Rh antigens: C, D, E, c, d, e
An individual has only a ‘C’ or a ‘c’, and a ‘D’ or a ‘d’, and a ‘E’ or an ‘e’
Only C, D & E are antigenic enough to cause development of anti-Rh antibodies
Therefore an individual possessing any one or more of these antigens is Rh+ (85% pop), while an individual having only c, d & e antigens is Rh-ve (15% pop).

Rh transfusion reaction:

Rh -ve person + Rh + blood

1) —> no immediate reaction

—> development of anti-Rh antibodies [2-4 weeks]

—> (in some indiv) agglutination of transfused rbc still in blood

—> delayed transfusion reaction (usually mild)

2) subsequent transfusion of Rh+ blood:

—>greatly enhanced transfusion reaction

Erythroblastis Fetalis

[agglutination & subsequent phagocytosis of fetal/infant rbc]
mother is Rh -ve father is Rh +ve Baby is Rh +ve
1st gestation: mother develops anti-Rh agglutinins but not enough to cause harm: are usually produced subsequent to parturition due to breakdown of placenta [this is the time to administer anti-Rh agglutinins which destroy circulating Rh+ agglutinogens thus preventing maternal development of anti-Rh+ agglutinins]
Subsequent gestations [with Rh+ child]: mother develops anti-Rh agglutinins rapidly upon becoming pregnant as she is now sensitized. . . they diffuse slowly into the fetal circulation causing a slow agglutination of the fetal rbc —> release of free Hb into blood —> increased bilirubin (kernicterus & jaundice) + clinically dangerous anaemia