CD19 and neoplasm: NK cells lead to B cell activation and induce class switching of immunoglobulins produced through CD40–CD40 ligand interaction and through the production of various cytokines.70 Additionally, B cell secreted antibodies may lead to antibody-dependent cell-mediated cytotoxicity by NK cells.70 Interestingly and in line with this, negative associations between the percentages of NK cells and CD19+ lymphocytes and tumour weight were observed in TDLN exclusively in H4R-KO mice.