BDCM stimulates T cell proliferation when the cells are co-cultured together for six days. Human peripheral blood lymphocytes isolated from freshly collected blood were labeled with CFSE on Day 0. CFSE-labeled lymphocytes were then co-cultured with BDCM cells at a ratio of 25 : 1 in 2 ml of RPMI culture medium in a 6-well plate for three or six days. Panel A : CFSE fluorescence intensity is strong at the time of staining (Day 0). Panel B and C : CFSE staining intensity drops rapidly in the first couple of days due to catabolism. As cell division occurs, the staining intensity stabilized (Day 3 and Day 6). Panel C : Eight peaks representing successive cell cycles of lymphocytes were detected after six days of BDCM stimulation (the first peak shown here actually contains two peaks representing undivided cells, peak 0, and first division cells, peak 1).