Histocompatibility Histocompatibility Systems Transplantation from one person to another are generally not successful because of the immune system.In an attempt to elucidate the genetic basis of graft rejection,investigators became interested in histocompatibility gene products that determine resistance or rejection.Later it became clear that these gene products participate not only in transplantation rejection,but are significantly involved in regulating immune responsiveness involving cell-to-cell interactions and in turn,susceptibility to a number of diseases. Rejection ☒ Xenogroft ifferent Species Mouse Rabbit Rejection ☒ Allograft Some species Mouse Graft is oh Isograft y人 Identical twins Inbred strain Graft is Ok Histocompatibility Histocompatibility Systems Transplantation from one person to another are generally not successful because of the immune system. In an attempt to elucidate the genetic basis of graft rejection, investigators became interested in histocompatibility gene products that determine resistance or rejection. Later it became clear that these gene products participate not only in transplantation rejection, but are significantly involved in regulating immune responsiveness involving cell-to-cell interactions and in turn, susceptibility to a number of diseases