You all know that just like your finger prints, your cells and tissues also have biochemical fingerprints.
Have you ever thought about how your body differentiates between a damaging invader such as a virus and your own cells?
The answer lies in a group of molecules called the Major Histocompatibility Complex molecules, or MHC. These tiny proteins are peculiar and function as a biochemical fingerprints enabling an individual’s immune system to differentiate between the self and non-self cells. Everyone has a different MHC molecules specific to their genes. This means that:
- Organ transplants are complicated: If the donor’s MHC type is not the same as the recipient’s, the organ may be regarded as foreign and the body’s immune system may reject it.
- Certain illnesses affect individuals in unique ways: Different types of MHC may predispose people to certain diseases such as autoimmune diseases or infections, while some types may be protective against them.
These MHC proteins found on the surface of most cells in your body. Lets understand this-Imagine a bucket (cell) full of water with different colour ball on surface of water (boundaries of cell), out of these one ball has different shape suppose rectangle with some piece coming beyond the water surface in free space. That’s how these MHC proteins are oriented on surface of cells. Without MHC, the immune system would not be able to know which cells belong to the body.
In short, there are two types of MHC: MHC Class I -Found in almost all cells in your body. It is a type of security software that displays protein units called peptides within a cell to the immune system. If a virus infects a cell, MHC Class I displays a “red flag” peptide which activates immune cells to demolish the infected cell.
MHC Class II – These are found on specialized immune cells, such as macrophages and dendritic cells. Exhibits peptides especially from bacteria which a cell has ingested to trigger other immune cells and response.
Imagine MHC as a tray holding samples of what’s happening inside a cell. Here’s how it works step-by-step:
- Sample Collection: The cell degrades proteins into smaller fragments known as peptides.
- Submission: MHC fetches these peptides and positions them on the exterior surface of the cell.
- Immune verification: T cells and other immune cells examine and confirm the presentation.
o If the peptides look normal, the immune cells continue with their activities.
o If the structure of the peptides is unfamiliar (false peptide such as fragment of a virus), the immune cells proceed to attack.
Did you know your MHC might even influence your sense of smell? Some studies suggested that people can subconsciously detect MHC compatibility through body odour, which might play a role in mate selection.
So, MHC is your body’s personal security system, constantly monitoring and protecting you from harm. It’s not just a biochemical fingerprint – it’s a testament to how intricate and intelligent our biology truly is. Next time you think about how your body fights off illness, remember the incredible role MHC plays in keeping you safe!
Dr Ranjana Agrawal
Vice Principal and Head
Department of Zoology
Kanoria PG Mahila Mahavidyalaya, Jaipur