This lack of immune control is related to low major histocompatibility complex (MHC) expression on B16 cells which is associated with delayed and decreased anti-tumour adaptive immune responses (e.g., alloantibody formation) as: (i) other tumour types with normal H-2Kb expression are rejected with concomitant antibody production; (ii) preincubation of B16 with IFN-gamma to upregulate H-2Kb expression resulted in improved antibody production and anti-tumour activity. This evidence concerns the gene HLA-C and neoplasm.