T Cell Immunity Regulation

To the tune of "I Will Survive" by Gloria Gaynor
If there are too few peptide-MHC complexes
The naive T cells, they will not be activated
The activation threshold has too high a requirement
And so these cells, they remain ignorant
Negative selection
Removes autoreactive T cells through clonal deletion
And those that do escape, deleted they will be
By induction of apoptosis in the periphery
Just signal one all alone
Can lead to apoptotic pathway activation
No costimulation by CD28
Means that anti-apoptotic genes are not upregulated
These responses regulate
Effector T cells so they don't cause damage through inflammation
T cell regulation has mechanisms
That help induce a healthy immune response
Lack of costimulation can cause anergy
Anergic cells can function regulatorily
Like if IL-2 is consumed by anergic cells
This can prevent T cell proliferation as well
Signal one upregulates
GRAIL and Cbl-b which are ubiquitin ligases
Parts of the TCR are ubiquitinated
Thus it becomes a target for protein degradation
The T cells that regulate
Kill effector T cells with methods like the CD8s
Such as the release of granzyme and perforin
Or chronic stimulation leading to exhaustion
These responses regulate
Effector T cells so they don't cause damage through inflammation
T cell regulation has mechanisms
That help induce a healthy immune response