Blood Grouping

Blood grouping refers to the total blood groups containing RBC antigens. The specificity of these RBC antigens is determined by certain sets of genes that can be allelic or linked very closely on the same chromosome. Blood grouping is a method to determine what type of blood a person has. It is genetically linked. One’s blood type is specified by what types their parents have passed onto them. The blood group becomes crucial for a patient during transfusion.

History of Blood Grouping

Till 1900, the death of a patient was far more prevalent when blood transfusion was attempted. There were many unanswered questions for biologists regarding blood transfusions. However, in 1901, eminent immunologist and pathologist Karl Landsteiner discovered blood groups, paving a new way for blood transfusions to be carried out safely. For this discovery, he was awarded the Nobel Prize in Physiology or Medicine in 1930. In 1902, the AB blood group was discovered by Alfred von Decastello and Adriano Sturli. The collective observations of Philip Levine, Rufus Stetson, Karl Landsteiner, and A.S. Weiner led to the discovery of the remaining blood group–the rhesus system.

Blood Components

Blood is majorly composed of plasma and other elements such as red blood cells, white blood cells, and platelets. Plasma comprises 60% of blood volume. It contains 90% water, 8% proteins, 1% salts, and traces of other substances. Apart from plasma, the other components of blood are

1. Red blood cells or RBCs (erythrocytes): these cells give blood the characteristic red colour. An average person has 4.5–5 million RBCs in the body. They are responsible for transporting gases like oxygen to various parts of the body. They are biconcave, devoid of the nucleus, circulate in the bloodstream for 120 days, and die in the spleen.
2. White blood cells or WBC (leukocytes): are the defence mechanism in the blood and key players of the immune system. An average person has 4000–11000 WBCs. The prime function of WBCs is to ward off any foreign pathogen or microbe that can cause disease.
3. Platelets (thrombocytes): are responsible for the blood clotting process at the site of injury or wound. An average person has about 200000–500000 platelets.

Observations Leading to Blood Groups and their Grouping

It was observed during blood transfusions that mixing two types of blood led to clumping, which blocked the circulation. The clumped RBCs crack and leak out contents from the vessels, causing fatalities. Karl Landsteiner discovered the compatibility between the blood groups of the donor and receiver to avoid clumping. To understand compatibility, one needs to know about blood groups and how they can be grouped.

Explanation of Blood Grouping

People need to know their blood groups, especially patients who need blood transfusions. There are several systems to correctly determine an individual’s blood type at times of need. The blood grouping explanation is as follows:

• The ABO system of blood grouping: according to this system, there are four types of blood groups, A, B, AB, and O.
• Blood group A has A antigens on the RBC surface and anti B antibodies in the plasma.
• Blood group B has B antigens on the RBC surface and anti A antibodies in the plasma.
• Blood group AB has both A and B antigens on the surface but no antibodies in the plasma. People with this blood group are universal recipients, as they can receive blood from any donor.
• Blood group O has no antigens on the surface but anti-A and anti B antibodies in the plasma. People having this blood group are universal donors as they can give blood to any patient.
• The Rh system of blood grouping: Rh or Rhesus factor is found on the surface of RBCs. People who have it are Rh+ while those who do not are Rh-. They do not have Rh antibodies in their blood plasma. However, an Rh- person can develop antibodies if they receive blood from a Rh+ person.
• MNS system of blood grouping: discovered by Landsteiner and Levine, this grouping system is based on Glycophorin A and Glycophorin B genes. They are controlled by LM and LN genes.

Importance of Blood Grouping

ABO incompatibility is the major cause of fatality because it causes haemolysis (RBC breakdown). Hence, accurate blood grouping is very important. ABO blood groups have a great influence in maintaining haemostasis.

Another important factor to check is the Rh system. A person with Rh- blood can develop antibodies from Rh+ blood. This happens in erythroblastosis foetalis, when an Rh- mother develops antibodies from the Rh+ father, leading to the death of the foetus during the second pregnancy.

During organ transplantations, blood groups are tested between the host and the donor to avoid rejection, GVHD (graft vs host disease), and patient death.

It can also be used for paternity testing. As RBC antigens are dominant traits, a child must have the antigens coming from the parents. It cannot have an antigen that is not present in one or both parents.

Conclusion

The unnecessary mixing of blood has led to several deaths during blood transfusions because of a lack of knowledge. After the remarkable discovery by Landsteiner, awareness about blood clumping spread. The discovery of blood groups and their grouping was of utmost importance as it saved numerous patients at times of blood transfusions. Be it for organ transplantation, blood donations, paternity testing, the discovery of blood grouping is of utmost significance to date.