How T cells 'see' antigen

It is Friday, the theory lunch time. I chatted with several people before the talk. Found we all liked the talk given by the Pfizer guy last week.

Today's speaker, Professor Arup Chakraborty, is coming from our dearest one-way rivalry neighbor, MIT. He wanted to talk about how the selection between APC and T cells can work as digitalized behavior, that is, bistability, either on or off; and models control the bistable senstivity threshold.

The topic is interesting, I will say. However, the speaker presented it with a less interesting way spending more than half of the time "teaching" the related mechansims which probably most of the people in the room had it learnt from the textbook already.

He found the Sos proteins might be the key protein to control such bistable behavior and did some simulations to confirm it. I don't know, maybe this piece of information is interesting to some people in similar fields. The talk then came to a point which I cannot stand anymore, so I left the room early.

(at least I had my stomach fulled!)

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How T cells 'see' antigen
15 February 2008

Arup Chakraborty
Laboratory for Computational Immunology
Departments of Chemistry, Chemical and Biological Engineering
MIT

Abstract
The orchestrators of adaptive immunity are a class of cells called T lymphocytes(T cells). They express T cell receptor (TCR) molecules on their surface, which recognize molecular signatures of pathogens. Each T cell expresses a distinct TCR, which can bind to short peptides (p) derived from pathogenic proteins associated with products of the major histocompatibility (MHC) genes; these pMHC molecules are expressed on antigen presenting cells. Sufficiently strong TCR-pMHC binding results in T cell activation. TCR bind weakly to endogenous pMHC molecules, thereby preventing frequent autoimmune responses. After briefly outlining how T cells detect minute numbers of pathogen-derived pMHC molecules, I will focus on how the specific, diverse, and self-tolerant T cell repertoire is designed in the thymus. I will detail how an approach that brings together theoretical and computational studies (rooted in statistical physics) with genetic, biochemical, and imaging experiments has allowed us to shed light on the pertinent mechanistic principles.

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