COMBINED CHEMOKINE AND CYTOKINE GENE-TRANSFER ENHANCES ANTITUMOR IMMUNITY

The probability of producing a specific antitumor response should be i ncreased by multiplying the number of T lymphocytes that encounter the malignant cells. We tested this prediction in a murine model, using a recently discovered T-cell chemokine, lymphotactin (Lptn). This chemo kine increased tumor cell infiltration with CD4(+) lymphocytes but gen erated little antitumor activity. Coexpression of the T-cell growth fa ctor interleukin-2 however, greatly expanded the T lymphocytes attract ed by Lptn, affording protection from the growth of established tumor in a CD4(+) and CD8(+) T cell-dependent manner. Lesser synergy was see n with GM-CSF. Hence coexpression of a T-cell chemokine and T-cell gro wth factor potentiates antitumor responses in vivo, suggesting a gener al strategy to improve cancer immunotherapy.