Allogeneic Inhibition in Thymectomized Animals lacking Homograft Reactivity

Abstract

THE phenomenon of allogeneic inhibition, a term coined by Hellström¹, was first observed by Snell et al.^2,3. These investigators noted that certain mouse lymphoma tumours grew less well in semi-syngeneic F₁ hybrid mice than in the original parental strain. Hellström^1,4 demonstrated that carcinoma and sarcoma growth was also inhibited in semi-syngeneic hosts. He thought it unlikely that the phenomenon was caused by a graft versus host reaction leading to “allergic death” of the tumour cells; or that allogeneic inhibition was caused by a homograft reaction directed against hypothetical recessive isoantigens of the tumour⁴, because all histocompatibility antigens of the mouse are codominantly expressed and F₁ hybrid mice are therefore genetically tolerant to parental strain grafts^5,6.