greatest immunology discoveries

[Esteban Celis]

In Article <38mhk9$d0n at jhunix1.hcf.jhu.edu>, ejf at welchlink.welch.jhu.edu
(Ephraim Fuchs) wrote:
>I would like to know what people think is the greatest advance in 
>immunology in the last 25 years.  


What about:

1) the discovery that T-cells recognize protein fragments (peptides) which
bind to MHC molecules?

2) Immunediversity and immunematuration in B cells created by somatic mutation?

3) The structure of T-cell receptor?

4) The cristal structure of MHC

5) Interaction between helper T cells and B cells

6) Thymic negative selection