[Decrease in radio-sensitivity of the tumor by radiation-induced damage to immuno-related cells]

Immunological competence plays an important role in response of patients to radiation therapy and dose of radiation required for tumor control depends also on the immunocompetence of the individual patient. Radiation therapy (even localized irradiation) can, however, cause lymphopenia and induce an immunodeficient state. This may facilitate growth of residual tumor cells or metastatic foci, this negating benefits of the therapy. A brief overview of damage to T and B lymphocytes as well as macrophages and natural killer (NK) cells by radiation therapy was presented. The restoration and potentiation of the immunological competence of the patients by biological response modifiers (BRM) such as OK432 (a bacterial preparation), recombinant interferon (rIFN-gamma) and recombinant interleukin-2 (rIL-2) with or without lymphokine activated killer (LAK) cells, were discussed.