I think it might be worthwhile to mention anergy here too. Even if a self
peptide is preseted, odds are a second costimulation through alternate
receptors (other than the TCR, eg CD28) are not supplied and the immune
system is tolerized to that antigen.
-Rachel
teitelba at aecom.yu.edu
On 4 Nov 1994, Ian A. York wrote:
> In article <199411041533.HAA01434 at net.bio.net> kdelgert at vt.edu (Klaus D. Elgert) writes:
> > A question arose in our graduate level immunology course. "How do
> >macrophages distinguish between self and non-self?" Macrophages are
>> I think there are two halves of your question: (1) How do macrophages
> endocytose foreign rather than self antigen and (2) how do they present
> foriegn material rather than self after endocytosis. The short answer
> is, they do not differentiate. This is true particularly at the level of
> presentation: self and foreign antigens are presented more or less at
> random (i.e. if an antigen has the appropriate motifs and the other
> caveats are met - cleavage, etc - then that epitope will be presented on
> MHC molecules. The discrimination here is at the level of the TcR;
> although self-antigen is presented by macrophages, the T cells simply do
> not recognize it. (Well, it isn't "simple," I guess.)
> As far as endocytosis is concerned, there is not very precise
> differentiation here between self and non-self antigens. There is some,
> however. As well as the opsinizing effects of antibody and complement,
> there seems to be some recognition of different lipids. I can't recall
> the whole story on this, but for example during apoptosis there appears
> to be alterations of the cell membrane, with a loss of the normal
> assymetry of the membrane; the normally hidden lipids act as opsinins and
> enhance phagocytosis. This probably is part of the red cell situation
> you mentioned. I believe there may be other opsinins which are exposed
> or prodced during apoptosis and probably other physiological states.
>> Hope this helps.
>> Ian
> --
> Ian York (york at mbcrr.harvard.edu)
> Dana-Farber Cancer Institute, 44 Binney St., Boston MA 02115
> Phone (617)-632-4328 Fax (617)-632-2627
>>
