CD4 and neoplasm: Research has shown that dendritic cells may potentially contributing to presenting tumor antigens to CD4 T cells, thereby promoting an anti-tumor immune response.17 Likewise, CD4+ memory T cells can recognize tumor cells and mount an immune response against them.18 Research has suggested that mast cells may secrete factors that promote tumor growth and metastasis, as well as factors that inhibit the anti-tumor immune response.19