HLA-C and neoplasm: However, all three approaches have relatively limited applicability.28, 29 Most importantly, many tumours evade the immune system by downmodulating surface expression of MHC molecules and/or adhesion molecules, especially within the CSC pool.30, 31, 32, 33 In agreement, the breast CSC-like cells in the present study expressed relatively low levels of MHC class I and CD54.