In support of this notion, experiments in the murine 2C TCR model system comparing TCRs of two distinct affinities, CD4+ T cells expressing an MHC class I‐restricted TCR with a 1000‐fold higher affinity (m33 TCR, KD = 30 nM) than the wild‐type (wt) 2C TCR (KD = 30 μM), were found to control tumour growth and persisted for longer periods in the mice, compared to similarly transduced CD8+ T cells, which were deleted in vivo soon after transfer 28, 29. Here, CD4 is linked to neoplasm.