Adenoviral vector-mediated p53 expression induced apoptosis is a well established gene therapy approach that has been evaluated extensively in epithelial tumors but only recently in lymphoid malignancies mainly due to the known resistance of the lymphoid lineage to adenovirus infection. Recently, it was shown that this resistance is not absolute and that cell lines derived from anaplastic large cell lymphoma (ALCL) and some other lymphoid malignancies are efficiently transduced by adenoviral vectors. Normal circulating T lymphocytes do not express coxsackie-adenovirus receptor (CAR) and alpha(nu)beta integrins and are relatively resistant to infection by adenovirus. These molecules serve as receptors for adenovirus entry into the cells. ALCL-derived SUDHL-1 cells were evaluated for transduction efficiency and expression of p53 after infection with an adenoviral vector containing wild-type p53 (AdWTp53). Cells derived from ALCL and circulating mononucleated cells (MNCs) were also evaluated for expression of CAR and alpha(nu)beta integrins. AdWTp53-mediated expression of p53 resulted in p21/WAF1 induction, G1 arrest, and apoptosis in SUDHL-1 cells. The expression of CAR and alpha(nu)beta5 integrin was high in SUDHL-1 cells and comparable to levels observed with epithelial tumor cells, but it was absent in MNCs. The susceptibility to adenoviral vector transduction of the tumor-derived cells implies an important biological difference between them and circulating MNCs, possibly underlying the malignant transformation that ALCL cells undergo. Further studies will be required to evaluate this initial observation in more cell lines and tissue derived from ALCL.