B2M and neoplasm: The low number of CD8+ T lymphocytes in the vicinity of or in contact with HRSC could be related to the frequent decrease or loss of β2M/MHC class I complex expression related to the inactivating mutations in β2M gene; conversely the CD4 richness around/in contact with HRSC may also be partly linked to the more frequent expression of MHC class II by the tumour cells.