Antigenic requirement for induced rejection of long-surviving murine heart transplants.

Primarily vascularized B10.BR mouse cardiac allografts survive long-term in untreated B6AF1 recipients. We found that sudden complete rejection of the grafts was produced by sequential "triple treatment" with BCG, cyclophosphamide, and a small number of donor-strain lymphocytes. Neither the graft itself, nor donor-strain platelets or frozen-thawed lymphocytes were an effective substitute for the intact donor-strain lymphocytes. Thus the long-surviving graft presents target antigens but lacks the antigenic characteristics required to stimulate a rejection response that are expressed on lymphocytes.