CD200 and B-cell chronic lymphocytic leukemia: Fig 3, shows the % loss of CD62L and CD200, across all patients, while S1a Fig shows individual data from 3 representative patients. By FACS analysis, CD200 levels were reduced by >20% on the surface of CLL cells from 4 out of the 6 patients following PMA stimulation, with a median loss at 44.2% and an average loss of 39.3% (±27.5%), supporting the hypothesis that CD200 was shed from the cell surface following PMA stimulation. Minimal evidence for apoptosis was seen in all cultures (S2 Fig).