Key Functions and Types of Agglutinins in Biology
Agglutinin meaning a substance present in the blood, agglutinin helps the bloodstreams to keep in coagulate and aggregate. It helps the blood to change from a fluid state to a thick mass state. The agglutinins are the antibodies that aggregate antigens by binding to the antigen-binding sites of antibodies. Agglutinins can also be other substances like sugar-binding protein lectins. Agglutinin causes coagulation of blood by typical antibodies present in the blood serums of normal human beings and animals. When agglutinin is added to the uniform suspension like bacteria, red cells, or protozoa that contains the specific antigen with which the agglutinin reacts against the objects by attached to each other. It forms clumps, falls to the button, and leaves the suspending diluent clear. This phenomenon is known as an antigen-antibody reaction. The phenomenon of agglutination is an antigen-antibody reaction. This is highly specific, reversible, and involving small reacting groups on the surface of each.
The greatest amount of particular antibodies is present in the individuals, which have been immunized with the specific antigen by infection or to activate immunizing procedures. Agglutination is used as an indirect test for past or present infection or immunizing with specific antigen, it indicates the presence of agglutinins in the serum. Agglutinin meaning the antigen present in the serum of blood, which are used to identify various bacteria, protozoa, and red cells. Isohemagglutinins is a substance, which agglutinates the red blood cells found in humans.
Types of Blood
The blood is made up of red blood cells, white blood cells, and platelets. The blood groups are usually identified by the antigens and antibodies in the blood. The plasma contains antibodies made of protein. This is the natural defense system in the body. The antibodies start to generate once the foreign substance like germs, bacteria enters the human body. Blood is majorly classified into four main blood groups. These are mainly grouped with respect to two antigens present in the red blood cells A and B and two isohemagglutinins anti-A and anti-B in the serum.
The types of blood
Blood Group A
Blood Group B
Blood Group AB
Blood Group O
Blood Group A: The person who has blood group A type contains antigen A and antibodies as anti-B in the plasma of red blood cells.
Blood Group B: The person who has blood group B types, will have antigen B and antibodies as anti-B in the plasma of red blood cells.
Blood Group AB: A person with AB blood group has no antibodies and A and B antigens in the plasma of red blood cells.
Blood Group O: A person with O type blood group have no antigens and both A and B antibodies present in the plasma of red blood cells.
Rh Systems
Red blood cells will have another protein, which is an antigen present in the plasma termed RhD antigen. If the RhD protein present in the blood plasma, it is known as RhD positive. It is absent in the blood plasma, it is known as RhD negative.
The blood groups are classified into 8 types based on its Rh systems.
A RhD positive (A+)
A RhD negative (A-)
B RhD positive (B+)
B RhD negative (B-)
AB RhD positive (AB+)
AB RhD negative (AB-)
O RhD positive (O+)
O RhD negative (O-)
Agglutination vs Coagulation
Both agglutination and coagulation increase the thickness of particles in a suspension. But they are different in certain aspects. Agglutination is the process of forming clumps in the blood. Whereas, coagulation is the process of formation of fibrin clots. When a blood cell wall is injured, the platelets get activated to stop the blood flow and form a plug to the wound site, this is known as coagulation.
Disease Caused By Agglutinin
Agglutinin causes some autoimmune diseases are known as cold agglutinin disease. During the cold agglutinin disease, the body synthesis agglutinins or antibodies which coagulates erythrocytes and lyse them at lower or room temperature. In a healthy human, the lifespan of erythrocytes is about 120 days. After that, they get degraded in the spleen. The main cause for cold agglutinin disease is the short lifespan of erythrocytes. The rate of erythrocyte produced by the bone marrow will be comparatively less than that of the rate of destruction results to cause disease like anemia. The human body produces agglutinins to attack the erythrocytes caused due to food allergies, inhalants, infections, and chemicals. A person who is experiencing this disease experience chillness in the fingers, nose, and ears. People who are living in warm areas experience these symptoms. The cold agglutinin disease usually provides symptoms like vomiting, diarrhea, ringing in the ears, dizziness, headache, etc. The major cause of cold agglutinin disease is a bacterial infection, viral infection, parasitical infection, and other immunodeficiency diseases.
FAQs on What Is Agglutinin?
1. What is an agglutinin in the context of human blood groups?
An agglutinin is a type of antibody naturally present in the blood plasma. Its primary function is to bind to specific antigens, known as agglutinogens, found on the surface of red blood cells (RBCs). This binding action causes the RBCs to clump together, a process called agglutination, which is fundamental for determining a person's blood type.
2. What is the main difference between an agglutinin and an agglutinogen?
The main difference lies in their nature and location within the bloodstream. Agglutinins are distinct from agglutinogens in the following ways:
- Agglutinogens: These are antigens (complex molecules like proteins) located on the surface of red blood cells. They act as identifiers that determine a person's blood type (e.g., A antigen, B antigen).
- Agglutinins: These are antibodies found circulating in the blood plasma. They are produced to react against specific agglutinogens that are not present on the individual's own RBCs (e.g., Anti-A agglutinin, Anti-B agglutinin).
3. How does the process of agglutination work?
Agglutination is a clumping process that occurs when agglutinins in the plasma encounter their corresponding agglutinogens on foreign cells, such as mismatched red blood cells. Each agglutinin molecule has at least two binding sites, allowing it to attach to antigens on several different RBCs simultaneously. This creates a cross-linked network or lattice, which pulls the cells together into visible clumps. This mechanism is crucial for both immune defence and laboratory blood typing tests.
4. Are agglutinins the same as antibodies?
Agglutinins are a specific type of antibody. The term 'antibody' refers to a broad class of proteins produced by the immune system to identify and neutralize foreign substances. 'Agglutinin' is a more specific term for an antibody that causes agglutination (clumping) of particulate antigens, like bacteria or red blood cells. Therefore, all agglutinins are antibodies, but not all antibodies cause agglutination.
5. What are the consequences of a blood transfusion reaction caused by agglutinins?
If a person receives an incorrect blood type, their native agglutinins will attack the foreign agglutinogens on the donor's red blood cells. This triggers a severe agglutination reaction within the blood vessels. The consequences are serious:
- The clumps of RBCs can block small capillaries, cutting off blood supply to vital organs.
- This is followed by hemolysis, the mass destruction of the clumped RBCs.
- Hemolysis releases a large amount of toxic hemoglobin into the bloodstream, which can lead to acute kidney failure, jaundice, shock, and potentially death.
6. Why don't a person's own agglutinins attack their own red blood cells?
This is prevented by a core principle of the immune system called self-tolerance. An individual's body only produces agglutinins against the agglutinogens they lack. For example, a person with blood type A has A-antigens on their RBCs but will only produce Anti-B agglutinins in their plasma. Their immune system is calibrated not to produce Anti-A agglutinins, thus ensuring that their own antibodies and red blood cells can coexist without causing self-agglutination.
7. How is the principle of agglutination used in medical diagnostics beyond blood typing?
The agglutination principle is a versatile diagnostic tool in immunology and microbiology. Its applications include:
- Bacterial Infection Diagnosis: Tests like the Widal test for typhoid fever mix a patient's serum (containing potential antibodies) with killed bacterial antigens. Clumping indicates a present or past infection.
- Microbial Identification: Known antibodies (agglutinins) are used in labs to identify unknown species of bacteria from a culture by observing if clumping occurs.
- Hormone Detection: Agglutination inhibition tests are used in some types of pregnancy tests, where the presence of the hCG hormone prevents a clumping reaction from occurring.
