Question

Give a brief account of Rh blood group incompatibility.

Answer 1

Rh factor was first reported in RBCs of Maccaca rhesus ( rhesus monkey) by Landsteiner and Wiener. Those having Rh factor are called Rh positive and those who lack are knows as Rh negative. Immunological incompatibility between mother and foetus sometimes results in a condition called haemolytic disease of the newborn. This disease was earlier knows as erythroblastosis foetails which occurs when the mother is Rh- and the foetus is Rh+ . When Rh+ Blood from the foetus enters the circulation of Rh-mother, antibodies against the Rh antigens will be produced. During childbirth, the foetal blood comes in contact with mother's blood . So the first Rh+ positive child is not affected, however the maternal circulation now contains antibodies and memory cells against the Rh antigen. A subsequent Rh+ foetus makes a secondary response from the maternal immune system resulting massive amount of antibodies. Rh+ antibodies cross the placenta in late stages of pregnancy and destroy the RBCs of the foetus. The resulting anaemia can kill the foetus before birth. Alternatively, hemoglobin is released from the destroyed RBC's is converted into degradation product which acts on the foetal brain causing severe mental retardation. Occasionally, the baby dies after the birth. Humans do not produce Rh antibodies naturally.