Self and Non-Self
Self
Non-Self
Detecting Self and Non-Self
MHC Markers
Similarities Between Self and Non-Self Cells
Differences Between Self and Non-Self Cells
- Describes agents that are recognised by the immune system of an organism as being part of that organism.
- All cells have MHC markers on their cell surface which help identify self cells.
Non-Self
- Describes agents that are not recognised by the immune system as being part of the organism its self.
- Non-self cells are classified as foreign and carry markers that identify them as non-self.
Detecting Self and Non-Self
- The immune system must distinguish between self and non-self cells so that they are able to identify cells belonging to the body and foreign cells that need to be attacked.
- The immune system co-exists with all the cells in the body without attacking them due to the cells have MHC markers enabling the immune system to identify these cells as belonging to self. Foreign cells present their own MHC Markers that the immune system recognises as non-self due to their MHC markers not being the same as cells belonging to the body.
MHC Markers
- Major Histocompatability complex.
- The MHC is a group of genes that code for the production of histocompatibility antigens on the external surface of all nucleated cells. These antigens are specific to the individual and identify all self cells.
- Class 1 MHC markers are found on the surface of all nucleated cells (all body cells except red blood cells)
- Class 2 MHC markers are found on the surface of B cells, T cells and macrophages.
Similarities Between Self and Non-Self Cells
- They both have MHC markers, however, these markers are not the same allowing the immune system to distinguish between self and non-self.
Differences Between Self and Non-Self Cells
- Self cells have MHC markers that the immune system identify as belonging to the body, where as, non-self cells have different MHC markers that the immune system identifies as being foreign to the body.
- Non-self cells will be attacked by the immune system to ensure they do not harm the body. Self cells are only attacked if infected and can be potentially harmful to the cell.