CTLA4 and neoplasm: Possible pathogenetic mechanisms include the increase in T-cell activity against neoantigens presented in both tumour and healthy tissues, the increase in pre-existing antigen-specific autoanti-body levels, bearing pathogenic potential, the increase in levels of pro-inflammatory cytokines, and increased inflammation mediated by the complement via the direct binding of anti-CTLA4 antibody, with the CTLA-4 receptor expressed in normal tissue.