The ability of a foreign particle (may be antigen or other parts of pathogen) to provoke our immune system and to induce a specific immune response (humoral or cell-mediated) is known as immunogenicity. The foreign substance which induces this type of immune response or causing immunogenicity is known as immunogen. These are high molecular protein- They induces the production of antibodies and binds to the T-cell. Immunogens can act in two different pathways- 1. Activating B-cell, 2. Activating T-cell.
- Activating B-cell: The immunogens enter into the organism and activate the B-cells and transform it into effector B-cell. Effector B-cells and memory B-cell. Effector B-cells developed into plasma cells and produces a specific antibody to this specific immunogenicity. The memory B-cell stored with this knowledge about the specific immunogen for future use.
- Activating T-cell: The immunogen activates the T-cell and transform it into effector T-cell and developed into cytotoxic and helper T-cell and induces the secretion of cytokines. Cytokines further carry the signal of this specific immunogenicity.
REQUIRMENTS TO INDUCE IMMUNOGENECITY: To become an immunogen a substance should have the following capability to provide immunogenicity.
- The immunogen must be a foreign substance for the host organism. Our adaptive immune system has the capacity to sense and eliminates the foreign antigens and have tolerance to our self-antigens.
- The immunogen should have a complex chemical structure because immunogenicity is increased with the chemical complexity of the immunogen. For this reason, the Heteropolymers are more immunogenic than Homopolymers.
- Immunogenicity also depends on the molecular weight. If the molecular weight (MW) of the immunogen is less than 1 KD then it is not immunogenic, if the MW is between 1-6 KD then it may be immunogenic or not, and if the MW is greater than 6 KD is good immunogenic. Large substance with high molecular weight increases the immunogenicity.
If any foreign substance (antigen or other) can maintain all the above criteria can become a good immunogen and can provide immunogenicity.
EXAMPLE: Vaccines are one type of immunogen that provide a specific immunity to a particular pathogen of a disease which helps us to be prepared to beat or fight against the disease. The process of injection of vaccines into our body is known as vaccination. Whole or some part of inactive or dead pathogen or antigen is used as vaccine to induce a specific immunity and provide immunogenicity. Immunogenicityit is very important for our body to fight against the pathogenic organisms.