As a prominent outgoing signal of CLL cells, MIF was predicted to interact with all antigen-experienced CD8 T-cell clusters via CD74, CXCR4 and CD44 (Fig. 6C), which is of interest as MIF was identified as a driver of CLL development in the Eμ-TCL1 mouse model33. Here, CXCR4 is linked to B-cell chronic lymphocytic leukemia.