Autologous or allogeneic T cells are genetically engineered to express a chimeric antigen receptor that binds lymphoma-associated surface antigens (e.g., CD19) independently of MHC. Antigen engagement activates CD3ζ and costimulatory domains (e.g., CD28 or 4-1BB), driving T-cell activation, expansion, and cytotoxic killing of tumor cells via perforin/granzyme release and cytokine production.