zehua007 at yahoo.com.cn wrote in message news:<20030412230354.3004.qmail at ww02.hostica.com>...
> The graft tissues do the same as the local one.
The MHC has little to do to the fact that a graft is considerd forign.
It's only showing what is made in the cells.But because different
people have small differens in antigenic expression this will lead to
that the lymphocytes are able to bind to MHC with its bound peptids.
When it's the bodys own cells protein fragment's that the MHC show
there isn't any lymphocytes that are able to bind. So it's small
differens on the cell proteins and carbohydrates and so on, that are
different in different individuals, that induces the immunosystem.