At the protein level, mean fluorescence intensity (MFI) was significantly lower in the CLL group as compared to the controls for BTLA in B cells (p = 0.039, Figure 2) as well as CTLA-4 molecules (both surface and cytoplasmic) on/in a BTLA+ B cell subset (0.006 and 0.0049, respectively; Figure 3). Here, CTLA4 is linked to B-cell chronic lymphocytic leukemia.