Superantigens

[William T. Lee]

In article <3jcjea$grs at newsbf02.news.aol.com>, fniner at aol.com (FNINER) 
says:
>
>The Seattle group showed in 1993, I believe, that the CD28 mediated
>stimulation is NOT essential for superantigen-mediated T-cell
>expansion/proliferation.  They used CTLA-4Ig as a B7-directed inhibitor
>and saw no effect on Superantigen-induced IL-2 synthesis or 
proliferation.
> Given opportunity, CD28 stimulation may augment the existing
>superantigen-induced response but its participation is not obligatorily
>required as some people would have us believe.  

This might be an interesting topic for discussion.  A recent paper by 
Blankson and Morse (Cell. Immunol. 157:306-312. 1994) indicated the 
oppostie.  In their system they used cells from a TcR Tg mouse and 
compared the response to both peptide and SEB.  The APC were (I can't 
remember off the top of my head whether it was a co-culture or a double 
transfectant with class II) B7-transfected fibroblasts.  Only in the 
presence of B7 was proliferation to either Ag or sAg seen.

In my own experiments using either normal or Tg T cells, the inclusion of 
Fab anti-CD28 blocks the response to both Ag or SEB by about 60-70%.  
This is in line with published inhibitory affects of Fab anti-CD28 or 
CTLA4-Ig, in in vitro assays.

Bill