Introduction
T cells orchestrate adaptive immunity,
via T cell rectoros (TCRs) that recognize short peptides from pathogen proteins.
T cell receoptors (TCRs) must be
Self-tolerant: to avoid auto-immune diseases
Diverse: to recognize an evolving landscape of pathogens
Specific: to lock on specific pathogens
What is the shortest peptide length that ensure sampling the entire (self) proteome?
In principle all human peptides can be recognized from sequences of length 5-6.
T cells are designed in the thymus gland,
where a diverse repertoire of thymocites is culled by encounters with self-pMHC, via
Positive selection: TCR must bind sufficiently strongly to at least one self pMHC
(implicated in MHC restriction, and sensitivity).
Negative selection: TCR must not bind any self pMHC too strongly
(deleting autoimmune TCR).
