Relevance of the absolute lymphocyte count in MDS. (A) Bone marrow CD19⁺ B lymphocytes demonstrate a significant increase in apoptosis, measured by annexin V staining, in MDS and RAEB-T patients compared with the other groups (P = .005 for all groups). The number of subjects included in each group is shown in parentheses. There was no significant difference between AML and healthy controls (P = .9), while the difference was significant (P < .05) between healthy or AML and MDS, RAEB-T, and CMML patients. The difference between healthy and anemia patients was marginally significant (P = .08). There was no significant difference between MDS, RAEB-T, and CMML patients. (B) Increased apoptosis as measured by mitochondrial membrane potential of total bone marrow lymphocytes is seen in MDS, RAEB-T, and CMML patients as compared with AML and control patients (P = .002 for all groups). The number of subjects included in each group is shown in parentheses. There was no significant difference between AML, healthy controls, and anemia patients (P < .05). There was significant difference between AML or healthy controls and MDS, RAEB-T, and CMML patients. However, CMML patients had significantly higher (P < .01) apoptosis than patients with MDS or RAEB-T as measured by mitochondrial potential.