NONSPECIFIC SYSTEMIC IMMUNE SUPPRESSION INDUCED BY PHOTODYNAMIC TREATMENT OF LYMPH-NODE CELLS WITH BACTERIOCHLORIN-A

Although photodynamic therapy is being used increasingly for the treat ment of cancer, its effect on immune responses has received little att ention. This aspect was studied in a rat model. Rats were given (intra venously) lymph node cells which were simultaneously exposed to a phot osensitizer and light. As a result of this treatment the animals showe d a decreased contact hypersensitivity response. Most important is tha t the generated immunosuppression proved to be non-specific. The conse quence of this finding may be that photodynamic therapy of tumours can inhibit the immune response against malignant cells.