In article <39k5vf$70h at dns1.NMSU.Edu> smori at nmsu.edu (Shahram Mori) writes:
>>We all know that macrophages do not phagocytose everything that they come
>across. If a free-flowing macrophage comes into contact with an antigen it
>will pick it up. However it doesn't pick up 'normal' host cells that are
>flowing in the blood. This would seem to require a way to differentiate
>between the foreign and the self. It may be that there is also ( early in
>development) pick up of self antigens but they go through the screening to
>be removed just like T and B cells do early in life.
It is true that macrophages do not phagocytose everything they
come across. It is not, really, true that they make some kind of
self/non-self decision at this point. However, I see that I may be
straying into semantics (not my original intention, I assure you.) Other
systems can make a self/non-self decision for the macrophage. For
example, things like complement systems activation, or antibody binding,
reslting in opsinization; the presence of bacterial-type membranes (help
me out here, somebody - I can't remember what it is in bacterial
membranes hat makes them an opsinin) enhances uptake. BUT the crucial
point is that macrophages DO present self antigen. And very
efficiently. I inclded references on this in my previous post.
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