In Situ Detection of Immunocompetent Cells in Murine B16 Melanoma Locally Treated With Interleukin‐2 or Microwaval Hyperthermia

Fidler's B16-F10 melanoma was locally treated either with recombinant interleukin-2 (rIL-2) or microwaval hyperthermia, and immunological responses of the host to the melanoma after each treatment were investigated by immunofluorescent staining of the tissue. It was found that the local injection of rIL-2 either into the base of the tumor or into the upper part of the tumor directly caused infiltration of mainly NK cells and macrophages in the interstitials and/or in the tumor nests. T cells were also observed but the extent of infiltration was less in both treatments. Local microwaval hyperthermia of melanoma at 42 degrees C for 30 min or at 43 degrees C for 15 min also caused infiltration of NK cells and macrophages. Positive staining of the melanoma tissue with anti-ICAM-1 antibody after hyperthermia was seen in the interstitials adjacent to melanoma nests containing necrotic melanoma cells caused by hyperthermia. Based on the results, the rationality of combination of hyperthermia with local injection of rIL-2 will be discussed.