Induction of tumor-infiltrating lymphocytes in human malignant melanoma metastases by immunization to melanoma antigen vaccine

We report a statistically significant increase in tumor-infiltrating lymphocytes in subcutaneous melanoma metastases removed from patients immunized with a melanoma vaccine. Dense cellular infiltrates were seen in 10 of 11 nodules from vaccine-immunized patients, compared with 9 of 22 nodules from non-immunized patients (p = 0.02). Furthermore, these dense lymphocytic collections more frequently infiltrated the body of tumor nodules from immunized patients, whereas in non-immunized patients, lymphocytes were more often present only in the dermal tissue at the periphery of the nodule. Thus, allogeneic melanoma vaccines may augment immune responses to a patient's own tumor.