Mutations in the WAS gene gave rise to DCs with a similar cell surface phenotype to normal DCs, but these DCs had a markedly reduced chemotactic motility and abnormal cytoskeletal organization : defects that would be expected to affect DC migration and maturation in vivo. More recently, intrinsic DC and T-cell defect in patients with autoimmune lymphoproliferative syndrome type II ( ALPS.II ) have been described. Two kindreds with missense mutations in the caspase 10 gene were found to have defective DCs that were protected from apoptosis signaled by FAS ligand and TNF-related apoptosis-inducing ligand (TRAIL); DCs ’lingered’ in the T zone of lymph nodes. Clearly such DCs that outstay their welcome could prime the observed autoimmune responses in ALPS II