Recombinant vectors are provided that render the proliferative response of activated lymphocytes, particularly cytotoxic T lymphocytes, of lessened dependency on T helper cells. The vectors are comprised of a region encoding a stimulatory factor polypeptide operably linked to a heterologous transcriptional control region. Expression of the stimulatory factor polypeptide from the recombinant polynucleotide in an activated lymphocyte renders the proliferative response of less dependent on lymphocyte T helper cells. When the lymphocyte is activated by binding of its cognate antigen the transcriptional control region causes transcription of the stimulatory factor encoding region. The cells containing the vector, particularly CTLs, are of use in immunotherapy.