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- เผยแพร่เมื่อ 11 ก.ย. 2024
- Blood grouping is very simple
A person having blood group A will have antigen A
As antigen A is self antigen, this group will not produce antibody for antigen A
For this group antigen B is foreign, thus they produce antibodies for antigen B
Similarly a person having bg B will have antigen B and antibody A
A person having Blood group AB will have both the antigens. Since both antigens are self antigens, it will not have any antibodies
Bloog group O contains no A/B antigen. Thus it shows the presence of antobodies gainst A and B both
We know that Blood group O individuals contain H antigen, then why is the discussion only about A and B antigens ?
Well H antigen doesn’t trigger an immune response, as you can remember from the structure, it is the basic structure of A and B antigen. So individuals having A, B/ AB blood group do no see H antigen as foreign and thus there is no immune response.
Due to this reason, for blood typing we only use antibody A and antibody B
For blood typing you can have 2 types of samples: blood sample/ serum sample
The blood sample contains all blood cells and coagulating factors
Thus if you have blood sample, you will have all RBCs showing the different antigen
When you allow the blood sample to coagulate, the clear liquid which is left behind is known as serum.
The serum sample is enriched with antibodies
In forward typing, we used the antigens present on RBCs and added commercially prepared antibodies to do blood typing
In reverse typing we use the serum of the patient.
Since in the serum antibodies are present, we must use commercially prepared antigens to obtain the antigen antibody reaction.
Now once you take blood from a person, you will add antibody A on one droplet and antibody B on another droplet and check for agglutination
If we observe agglutination In the presence of antibody A, this means that the blood contains antigen A. Also there is no agglutination in presence of antibody B, thus antigen B is absent. So we can say that the person is of blood type A
Similarly if there is agglutination for the droplet where antibody B was added in the blood and not for antibody A, we can say the person has antigen B, but no antigen A, and so they are of blood type B
If agglutination is seen for both antibodies, both antigens are present, and it is blood type AB
Whereas if no agglutination is seen for any antibodies, we can say that both antigens are absent, and it is blood type O
If we observe agglutination In the presence of antigen B, this means that the serum contains antibody B.
Thus we know that if the person has antibody B, they do not have antigen B
Also there is no agglutination in presence of antigen A, thus antibody A is absent. So we can say that the person is of blood type A
