Photodynamic therapy with photoactivated aluminum disulfonated phthalocyanine and cellular immune response

Photodynamic therapy (PDT) of cancer is based on the systemic administration of photosensitive drugs followed by exposure of the tumor mass to light of particular wavelength. The combination of drug uptake in malignant tissues and selective delivery of laser-generated light provides for an effective therapy with efficient tumor citotoxicity and minimal normal tissue damage. There are various studies on the effect of photoactivated photosensitizers on host immune response in tumor bearing mice. Since immunity is important in the control of tumor growth and spreading, in our laboratory we examine the effect of PDT on immune compartment. Spleen hyperplasia as well as spleen and marrow hypercellularities were observed in tumor bearing mice treated with Aluminum Disulfonated Phthalocyanine (AlS2Pc) and laser light Phytohemagglutinine (T lymphocytes mitogen) and Lypolisaccaride (B lymphocytes mitogen), stimulation of spleen lymphocytes caused an increase in blast transformation in tumor bearing mice. Furthermore splenocytes and macrophages collected from mice treated with PDT were cytotoxic in vivo (Winn Assay) parental against tumor cells. The results observed suggest that PDT is able to modulate the immune response and oncological patients treated with PDT could become immune versus a relapse or versus the minimal residual disease.