Allorecognition occurs when the host immune system detects same-species, non-self
antigens and this is the trigger for allograft rejection. Host T cells detect these
'foreign'antigens which are mostly derived from a highly polymorphic region of the genome
called the major histocompatibility complex. Allorecognition can occur by two distinct, but not
mutually exclusive pathways: direct and indirect. The direct pathway results from the
recognition of foreign major histocompatibility molecules, intact, on the surface of donor …