Let me put this in very simple terms. There are billions and billions of different t-cells ready willing and waiting to be triggered if a certain disease enters the body.
Essentially, evolution has allowed this massive memory by including these billions and billions of t-cells that are different from each other.
When a dendritic cell nibbles or sometimes engulfs a tumor cell, it internally breaks it apart, then moves the antigens back to the outside of its cell onto long arms called MHC molecules.
Then, It has to be a t-cell from billions of differentiated t-cells that has the right “lock” for the foreign antigen “key” that will lock up with the antigen expressing dendritic cell to start the process of expression.
The billions of t-cells different from each other circulating in the body are essentially an individualistic memory from evolution of what’s foreign or “bad”.
This way the body won’t attack itself.
See my previous post for a simple explanation regarding dendritic cell expression to the t-cells.
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