What is Agglutinin?

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

  1. Blood Group A

  2. Blood Group B

  3. Blood Group AB

  4. 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. 

  1. A RhD positive (A+)

  2. A RhD negative (A-)

  3. B RhD positive (B+)

  4. B RhD negative (B-)

  5. AB RhD positive (AB+)

  6. AB RhD negative (AB-)

  7. O RhD positive (O+)

  8. 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 (Frequently Asked Questions)

Q1. What is Agglutinin and Agglutinogen?

Ans: While grouping the blood, the blood group determination occurs depends on the presence of antigens and antibodies present in the red blood cells. Here, the presence of the antigen on the surface of the red blood cells is known as agglutinogens. The agglutinogens are the protein that exists on the surface of the red blood cells in the body.  Likewise, the antibodies, which react to agglutinogen are termed agglutinins. Usually, the antibodies in the blood encounter in the plasma. Any substance that acts as an antigen stimulates the production of specific agglutinin. The types of human blood can be classified into two major groups based on the presence or absence of agglutinogen.   

Q2. What Agglutination Means?

Ans: The formation of clumps of cells or inert particles with specific antibodies as surface antigenic components or antigenic components adsorbed or chemically coupled to red cells is known as agglutination. Agglutination is induced in the blood through agglutinins. Agglutination is of three types they are direct agglutination, passive agglutination, and passive hemagglutination. Examples of agglutinins are lectins and antibodies.  According to microbiology and immunology, the term refers to the bacterial cells that clump in the presence of an antibody or a compliment. 

Q3. How Do Agglutinins Work?

Ans: When agglutinin is added to the uniform suspension of particles like red cells, bacteria, or protozoa. Each contains the specific surface structure, on which the agglutinin reacts to the suspended object by attracted together. It forms clumps, falls to the bottom, and leaves the suspending diluent clear. If the agglutinins do not suit the body of the blood, clumps or agglutination of red blood cells on the surface of the red blood cells cannot pass through the small tubes of various organs. This may result in organ failure or destruction of red blood cells or hemolysis.