Topic 8: Human and animal blood groups

Question 1

What should be mentioned in this topic?

Answer 1

• Basics about blood groups
• Hemagglutinogens
• Formation of Hemagglutinins
• Agglutination
• Human Blood Groups
• AB0 Blood Type Reactions
• Rh Blood Group
• Rh-incompability
• Animal Blood Groups
• Blood Transfusion

Question 2

Basics about blood groups

Answer 2

Blood groups are complex antigens appearing in the surface of the blood cells. There are about 15 types of human blood groups (two of these are AB0 and Rh). They provide an important role during blood transfusions.
Antibodies are produces postnatally against those human red blood cell antigens that the person does not possess. They circulate in the plasma. These antibodies agglutinate other individuals’ red blood cells. Blood transfusion means less trouble in animals than in humans for two reasons:
There are only few naturally produced antibodies against RBC antigens. The antigens against which antibodies can be found in other individuals can be found not only on the red blood cells, but in the plasma too. Therefore in case of transfusion the antibody is neutralised in the plasma already and its RBC dissolving capacity diminishes.

Question 3

Hemagglutinogens

Answer 3

They are compounds on the surface of the RBC forming antigens. Substances initiating the production of the blood-agglutinating-antibody.

Question 4

Hemagglutinogens:

Natural Hemagglutinogens

Answer 4

• Antibodies are present without previous immunisation

- Agglutinate the red blood cells of animals expressing the corresponding antigens

Question 5

Hemagglutinins:

Artificial Hemagglutinins

Answer 5

• Antibodies form only after previous immunisation
• Immunisation can be
  o Natural–Rh
  o Artificial

Question 6

Hemagglutinins:

Hetero/Isohemagglutinins

Answer 6

• Hetero-: Agglutinates RBCs of the other species

- Iso-: Agglutinates RBCs of the same species

Question 7

Formation of Hemagglutinins

Answer 7

• Early immunisation postnatally
• Antibodies are not present in newborn
• Antibody titer is constantly growing
• Antibodies may disappear in elderly individua ls

Question 8

Agglutination

Answer 8

The reaction between the RBC and the plasma antibodies occurs in two basic forms:
- Agglutination
- Hemolysis
- These two reactions occur together or alone. In case of human blood the first reaction is
significant, in case of animal blood, the second is more typical.

Question 9

Human Blood Groups

Answer 9

The H antigen encoded by the H gene forms the basic structure of the most important blood type system (AB0). There are further groups synthesised on this which is why A, B and AB groups are formed. If there are no additional groups the 0 group is formed.

A antigen: N-acetyl-galactose-amine transferase enzyme forms the A blood group antigen.

0 antigen: suppresses the production of N-acetyl-galactose-amine transferase enzymes. Accordingly no A or B blood group is formed and the 0 group appears.

B antigen: galactosyl-transferase enzyme forms the B blood type antigen.

Question 10

AB0 Blood Type Reactions

Answer 10

• Type of a red blood cell belonging to an unknown blood group can be determined by agglutination reaction.
• We have the blood cells bearing unknown A, B or AB antigens react with a serum containing specific antibodies directed against the antigens.
• In case of incompatibility agglutination is seen, that can be used for determination of the blood cells’ antigen-type.

Question 11

Rh Blood Group

Answer 11

Rh negative mother can be immunised by the blood cells of her own Rh positive foetus. The forming antibody is not IgM- type like in the AB0 case, but IgG-type that crosses much easier the placenta. In case of the first foetus no damage occurs because the foetal RBC usually gets into the mother’s body only via micro-injuries during the delivery.
During the second pregnancy the small amount of RBC entering the mother’s sensitised immune system stimulates the production of anti-Rh antibodies that dissolve the foetal red blood cells and a clinical pattern called erythroblastosis feotalis occurs causing yellow jaundice and in its last stage, the death of the foetus.

Question 12

Rh-Incompatibility

Answer 12

The other important case of Rh-incompatibility is when an Rh negative recipient gets RBC from a Rh positive donor. The Rh-negative recipient is immunised and the forming IgG antibody dissolves the red blood cells of the recipient.

Question 13

Animal Blood Groups

Answer 13

The animal blood group systems significantly differ from those of the human ones.
-In most cases there are no naturally formed antibodies against the RBC-antigens of other individua ls.
-In many cases the blood type antigens appear in the plasma, too.
-Most of the time the artificially formed antibody has a haemolysing and not an agglutinating
character.

Question 14

Blood Transfusion

Answer 14

Substitution of lost RBCs and assuring normal gas transport.
In large animals a small amount is first transfused. If there is no sign of incompatibility the whole amount is transfused.
In small animals the three drop test must be always completed; 1 drop of donor blood cells, 1 drop of recipient’s plasma and 1 drop of physiological sodium chloride solution. If there is no hemolysis or agglutination, the transfusion can be completed without the complete knowledge about the blood groups.
For cat as a life saving act blood of a donor dog can be transfused.