Understanding the Rh Type of Blood Grouping

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RH blood Grouping and ABO blood grouping. While some people are very used to the Rh- Blood grouping system, it is important to know that the ABO blood grouping system is well recognized and they both work hand in hand. Please do not mistake blood grouping for genotypes, they are not the same in any way. the Rh-blood grouping has to do with antigens and antibodies but before I continue what is the meaning of 'Rh'according to "The A-B-O blood groups of rhesus monkeys" shows that it means Rhesus Monkey. This occurred as a result of an experiment where red blood cells from a rhesus monkey were injected into a rabbit and a guinea pig. When this transfusion was done, it was noticed that the guinea pigs developed antibodies that agglutinate the red blood cells from the rhesus monkeys because the red blood cells of the rhesus monkey had antigens that were foreign to the Rabbit system causing the rabbit to produce antisera that fought against the antigen. This led to the conclusion that the rhesus monkeys had antigens known as rhesus antigens. When tested with human red blood cells, the rabbit also produced antisera which were able to agglutinate the red blood of almost 85% of the humans used to test basically Caucasians, but about 15% of the population were not agglutinated by the antisera. This led to the belief that 75% of the white population had something in common with the red blood cells of monkeys. These led to a hypothesis that people who fell under the 75% category had a red blood cell that was Rh positive, while people who did not react to antisera were said to be Rh Negative blood type.


[https://commons.wikimedia.org](https://commons.wikimedia.org/wiki/File:Blood_Group_Chart_Designed_by_((Sir_Ibrahim_Awwab))_29_July_2018.png)

In recent times, we have learned more about Rh antigens and we know that there are about 50 Rh antigens but clinically, some are very important while others do not pose much importance. Rh antigens are proteins or peptide chains that pass through the red blood cell membrane 12 times, and that is why it is known as 12-Pass membrane proteins and they are an integral part of RBC proteins. The antigens that are important include the D-antigen, C/c-Antigen, and E/e-antigen. The antigens are also known as Factors, so when you hear factors, you should understand that antigens are being referred to. The Rh factors are made in the erythroblast where RhD is made up of the RhD gene and the RhC, Rhc, RhD, and Rhd are determined by the presence and function of the RhCE genes.

Back to the Rh antigen factors, the D antigen is the most important factor clinically as it is most commonly found and most immunogenic. People who do not have the D antigen in their blood are Rh-negative. So when patients are Rh-positive, it means they are D-positive and when they're Rh-Negative, it means they are D-negative and patients can have weak d-positive antigens as the number of D antigens is low. D antigen has 4 antigenic determinants/epitopes. With the Rh antigen classification, a person can be said to have Rh-Null when they do not possess any of the five antigens. So when we are to identify positive and negative blood groups, the D antigen is used as a factor.


(https://commons.wikimedia.org

The ABO system antigens use carbohydrates as antigens instead of proteins like the Rh blood grouping. They are chains of oligosaccharides which are the Blood group A with one type of chain having A antigens in their red blood cells, the blood group B with different types of chains and have the B antigens in their blood group, and the blood group O do not have the A antigen and the B antigen in their blood. It is important that you remember that Rh antigens are proteins while ABO antigens are Oligosaccharides. People can have A antigens on their red blood cells, making them a member of the blood group A, people with B antigens in their RBC are referred to as members of the blood group B. People who have both antigens in their red blood cells are referred to the AB blood group while people who do not have any of the antigens are referred to as the O blood group. With the ABO blood grouping already explained, checking if the blood has the D- antigen in the Rh blood grouping will determine its positivity or negativity. If an AB blood group has a D antigen, it will be defined as AB Rh +, and so on.



Citation
https://pubmed.ncbi.nlm.nih.gov/6771406/

https://www.jstor.org/stable/30080584?seq=1

https://www.sciencedirect.com/topics/medicine-and-dentistry/blood-group-rhesus-system

https://www.ncbi.nlm.nih.gov/books/NBK2269/

https://ashpublications.org/blood/article/95/2/375/138582/The-Rh-blood-group-system-a-review

https://www.ncbi.nlm.nih.gov/books/NBK2267/



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2 comments
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This issue is undoubtedly very important, since an error in this classification when working with a patient's blood can cause the patient's death.

I particularly feel a lot of respect for those who work in blood banks, who know all this very well.

It is an interesting story all that is involved in the discovery of the blood groups and the Rh factor, you have explained it quite well.

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