CD28 and neoplasm: The difference in CD24 expression between T cells and B cells is that CD24 is upregulated on activated T cells.247 CD24 deficiency and CD28 deficiency synergistically suppress CD4 and CD8 T-cell responses.248 In addition, highly expressed CD24 on tumor cells binds to Siglec-10 on the surface of T cells and B cells, inhibiting TCR and BCR-related kinases to block activation of the TCR and BCR and ultimately promote tumor immune escape.