APC targeted Ag: can it direct Th1 or Th2 responses
R M Bernstein
ralph at ccit.arizona.edu
Thu Oct 5 16:48:02 EST 1995
In Article <M_Doherty-1109561055370001 at db425.niaid.nih.gov>,
M_Doherty at NIH.gov (M. Doherty) wrote:
>>Oh, OK, I see. There are two problems with that - B7.1 and B7.2 are
>>expressed on the APC, rather than the cells stimulated, which bind either
>>of these molecules through CD28.
Rite, sorry i mistated, i get excited about this. what i mean is cd28 and
ctla 4. see below
>>The second problem is that these markers
>>fluctuate - macrophages are normally devoid (or nearly so - even that is
>>controversial) of B7.1. However activation can cause it to be
>>upregulated. Regulation of B7.2 also occurrs, so they don't seem to be
>>ideal markers for cell types. Of course as we learn more about
>>distribution/role of these molecules they may become useful stage-specific
>>markers for certain cell types.
Rite, but what clears things up for me is that B71 was supposed to be the
low affin to cd28, and b72 was the higher affin to ctla 4 (or visaversa, i
sometimes get them confused). supposedly, when a second signal was given,
ie b71 ligating the cd 28 the same time tcr is ligated, the tcell activities
of the cell are upregulated. when this occurs, all the cytokine, etc,
signalling tells the mphage to up reg b72 which binds ctla 4, which
_downregs_ b71, stopping the 2nd ary signal controlling the immune response.
was supports this (to me) was what you mentioned in a prev post, that b72 is
tied in with il 4 levels. this makes sense because il 4 is antagonistic to
th1> it helps to switch or is indicative of a th2 type response. so if b72
does a th2 type response along with il 4 , then that paper is spot on. more
to add: the cd 28 may be on the th1 cell, and the ctla 4 may be on the th2
type cell. so maybe someone will see that ifn gamma and th1 and cd 28 and
b71 all go together? or a th1 cytokine profile goes with cd 28, and a th2
profile goes with ctla 4?
admittedly this is speculative, but to me it could make sense. and i love
it when a "big picture" falls into place.
Ralph M. Bernstein
Dept of Micro/Immuno
University of Arizona
Ph: 602 626 2585
Fx: 602 626 2100
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