HLA-C and neoplasm: Once a CTVT is regressing or has entered a stationary phase, the host dog is immune to re-inoculation, and this immunity can be transferred via sera to naive dogs.63,64 The sera of these dogs contain IgG that will coat tumour cells and can mediate rapid killing via antibody-dependent cell-mediated cytotoxity.55,65 The antigens on CTVT cells that trigger this response have not been characterized in detail, but they are likely to include both MHC and non-MHC encoded molecules.66