Since a multitude of cellular processes are involved in the processing of antigen, loading on and transport of MHC II, leading to antigen presentation on the plasma membranes of APCs33, we followed up the flow cytometric study by investigating whether the total amount of I-Eα and HLA-DRα is affected in isolated mouse caspase-2−/− B-cells and caspase-2-silenced human leukemia cell lines, respectively. This evidence concerns the gene HLA-DRA and leukemia.