Blood Groups

Question 1

How are blood groups determined?

Answer 1

The cell membranes of RBCs have antigens (also called agglutinogen) which determine the blood group

Agglutinogen = anntigen
Agglutinin = antibody

Question 2

What are the two systems of antigens affect blood transfusion?

Answer 2

• O-A-B system
• Rh system

There are over 30 commonly occuring antigens on the surface of RBCs; only these two systems can provoke immune reactions strong enough to affect blood transfusion

Question 3

In the OAB system, how do RBCs differ from each other?

Answer 3

Blood group A: Genes synthesizing antigen A
Blood group B: Genes synthesizing antigen B
Blood group AB: Genes synthesizing antigens A and B
Blood group O: Neither antigen synthesized

Question 4

Antigens of the OAB group

Answer 4

Anti-A antibodies: Destroy RBCs with antigen A
Anti-B antibodies: Destroy RBCs with antigen B

If antigen and antibody interact, hemolysis (destruction of the RBC occurs)

Question 5

What antibodies are present for each blood group?

Answer 5

People with …:
* … blood group A = anti-B antibodies
* … blood group B = anti-A antibodies
* … blood group AB = no antibodies
* … blood group O = anti-A and anti-B antibodies

All these aggultinins are gamma globulins (IgM and IgG)

Question 6

What three alleles determine blood group in the ABO system?

Answer 6

A, B and O

Question 7

How does each allele in the ABO system affect blood group?

Answer 7

O allele is recessive.
A and B alleles are dominant to O allele and co-dominant if present together

Question 8

What causes the formation of anti-A and anti-B antibodies?

Answer 8

Small amounts of type A and B antigens enter the body in food, bacteria, etc. which initiate the development of the anti-A and anti-B agglutinins.

Question 9

Where are the gamma globulins produced?

Answer 9

Bone marrow and lymph gland cells.

Question 10

Describe the period during which agglutinins begin to increase?

Answer 10

At birth = agglutinin level is 0
2-8 months after birth = agglutinin starts rising
8-10 years old = agglutinin reaches its max and declines in the remaining years

Question 11

What is Rh group/agglutinogen D?

Answer 11

Rh-positive means that the individual has agglutinogen D (85 % of population)
Rh-negative means that the individual has no D-antigen (15 % of population)

The anti-D-agglutinins are formed when Rh negative individual received Rh positive blood that has the D antigen