Blood grouping system : ABO type

Determination of blood grouping: ABO blood group system

Karl Landsteiner, the American -Austrian pathologist first discovered the ABO blood grouping system in 1901.This system is the most important blood group system in a human-blood transfusion. Persons ABO blood type is determined by the hereditary presence or absence of RBC agglutinogens  A and B.

Blood mainly divided into two different portions after centrifuged, the plasma and the blood cells.

1. Plasma:

Plasma basically contains water, proteins, carbohydrates, enzymes etc. Human plasma also contains important components, such as immunoglobulin (antibodies), clotting factors, and the proteins albumin and fibrinogen. It constituent 55% of total blood volume. It is yellow fluid like the color of straw.

Functions:

·       The main function of plasma is to transport protein, hormones and nutrients in the body.

·       Remove waste products from the body.

·       It is also played role in the circulatory system by moving elements of the blood.

·       Plasma is a critical component in the treatment of many serious health problems.

Serum:

The serum is yellowish, clear blood fluid which is blood plasma without clotting factors. It does not contain blood cells. So in a word, the plasma without clotting factor is serum.

             Serum = Plasma – fibrinogen (clotting factor)

2. Blood cells:

Hematocyte or blood cells are mainly three types. They are..

·       Red blood cells – Erythrocytes

·       White blood cells – Leukocytes

·       Platelets – Thrombocytes

Red blood cells:

These are so named for their bright red color. They are the most abundant cells in blood about 40-45% of cell volume. They are produced as immature cells in bone marrow. They can survive on average 120 days and can easily change their shapes. The percentage of whole blood volume that is made up of them is called the hematocrit and red blood cell levels can be measured from them. The red color is formed by a protein called hemoglobin, which helps carry oxygen from the lungs to the rest of the body and then returns carbon dioxide from the body to the lungs so it can be exhaled.

White blood cells:

They are much fewer than red blood cells about 1% of total blood volume. They contain neutrophils which help us to protect from infectious agents, but they live less than a day. So our bone marrows have to continuously produce them. T lymphocytes can regulate the immune cells and directly attack various infected cells and tumors. B lymphocytes can make antibodies, which are proteins that specifically target bacteria, viruses, and other foreign materials.

Platelets:

Platelets help the blood clotting process by gathering at the site of an injury, sticking to the liner of the injured blood vessel, and forming a platform which blood coagulation can occur. This leads to the occurrence of a fibrin clot, which provides coverage for the wound and prevents blood from leaking out. Fibrin also forms the first scaffolding where new tissue forms, thus promoting healing.

A higher than normal number of platelets  may cause unnecessary clotting, resulted in strokes and cardiac arrest; however, due to advances made in antiplatelet therapies, you will find treatments available to help prevent these life-threatening events. Conversely, less than normal counts can result in extensive bleeding.

Properties of ABO blood groups:

• Group A – has only the A antigen on red cells (and B antibody in the plasma)
• Group B – has only the B antigen on red cells (and A antibody in the plasma)
• Group AB – has both A and B antigens on red cells (but neither A nor B antibody in the plasma)
• Group O – has neither A nor B antigens on red cells (but both A and B antibody are in the plasma)

Characteristics of ABO antigen:

Naturally ABO antigens are glycoprotein where oligosaccharides directly attached to the lipid on RBC membrane. Besides their presence on red blood cells, soluble antigens may be contained in plasma, saliva, as well as other secretions. These antigens will also be expressed on tissues apart from red cells. This last fact is important to consider in organ transplantation.

Characteristics of ABO antibodies:

The antibodies in the ABO system are generally naturally occurring, i.e., they may be non-red cell stimulated. They could also be called regularly-occurring if an antigen is missing; the related antibody is obviously present. They react saline and readily agglutinate. They have a 30`c optimum temperature, but they react at body temperature.

The Blood Types

The ABO blood typing system groups your blood into among four categories:

• O: type O individuals can donate blood to anyone, but can receive blood only from other type O individuals.
• A: type A individuals can donate to type A individuals and type B individuals. Type A individuals can receive blood only from another type A individuals and type O individuals.
• B: type B individuals can donate blood with other B individuals and AB individuals. Type B individuals can receive blood only from type B individuals and type O individuals.
• AB: type AB individuals can give blood just to other AB individuals, but could receive blood of any kind.

Then, there is a Rh factor blood grouping system:

• Rh+: Individuals with Rh-positive blood have Rh antigens on the surface of their red blood cells. Individuals with Rh+ blood can receive Rh+ or Rh- blood.
• Rh-: Individuals with Rh-negative blood do not have Rh antigens. Individuals with Rh- blood can receive only blood that is also Rh-.

Together, the ABO and Rh grouping systems yield your complete blood type. There are actually eight possible types: O+, O-, A+, A-, B+, B-, AB+, and AB-.

Test procedure:

It is crucial that everybody know their particular blood group which of their close relatives. There are lots of occasions when knowing your blood group could be important, for example, if you or a member of your  family, required an urgent blood transfusion it would be useful to know your blood group ahead of time. Whether it was an infrequent group may well permit the hospital valuable time to be sure adequate supplies.

How accurate is this test:

The test is accurate and can detect the common blood grouping system A, B, O, AB and Rhesus(D). Unusual blood groups or rare sub-types won't be detected by this method. Further investigation with a blood transfusion laboratory is going to be essential to identify such groups.

Requirements:

·       Instruction leaflet
·       Blood group result card
·       Lancets
·       Plastic pipette
·       Alcohol swab x 2
·       Water
·       Applicator or Eldon stick
·       Slide

Precautions:

• ·       The slide can only be used once
• ·       Do not use this test if the foil pouch continues to be opened
• ·       Perform test at room temperature
• ·       Don’t smear the blood above the skin.

Instructions:

Read the entire instructions before carrying out the actual test. Ensure the applicators (Eldon sticks) are only used for stirring and spreading the blood. You may find this test easier to carry out if you have a friend or member of the family assist you.

·       Wash your hands before carrying out the test and again after carrying out the test.
·       Open the foil pouch containing the test slide.Place the slide on a table or flat surface.
·       Lay the applicators (eldonsticks) ready to be used.
·       Fill a little cup with tap water and taking advantage of the plastic pipette, draw a little amount of the tap water into your plastic pipette. You draw water by simply holding  the tiny, thin end in the water and squeezing  the very best part.
·       With the test slide still on a flat surface release one drop of water onto it.
·       Twist off the little green protective cap from your lancet. Put the lancet upon a table.
·       Wipe a fingertip with the alcohol impregnated tissue provided and allow it to dry.
·       Place the lancet against the end of the finger and press the green body against your finger release the needle.
·       Massage the finger from your bottom to the peak to encourage blood flow. Press the blood towards fingertip. Repeat pressing until a drop with a 3 to 4 mm (1/8 inch) diameter is seen.
·       Transfer the blood a great Eldonstick, approached from underneath the finger.
·       Place the eldonstick using the drop of blood into the first circle. The blood should touch the water already present. Gently press the inside of the eldonstick head up against the slide and stir in the water and blood mixture until the coloured dry material has dissolved.
·       Repeat this procedure for the other 3 circles, making sure you use a new eldonstick for each circle. You should never  transfer liquid from one circle to another.
·       Once all 4 circles are complete gently tilt the whole card vertically on its bottom edge and keep this position for 10 seconds. You will see the blood flowing slowly to the bottom of the circle. Repeat this procedure tilting the card on the 3 other sides.

·       You will see the blood flowing slowly to the bottom of the circle.

·       As soon as you have finished tilting read and record the final results immediately.

In order to determine your blood type, you will mix your blood sample with antibodies that attack types A and B blood to see the way reacts. In case your blood cells clump together when combined with antibodies against type A blood, for instance, you've type B blood. Your blood sample will be combined with an anti-Rh serum. In case your blood cells clump together responding towards the anti-Rh serum, this means you have Rh+ blood.