Korbelik, Mladen and Jinghai Sun, 2004, Cancer Immunology, Immunotherapy 55:900-909.
(1) British Columbia Cancer Agency, 675 West 10th Avenue, Vancouver, V5Z 1L3, BC, Canada
Received: 28 April 2005 Accepted: 20 September 2005 Published online: 8 October 2005
A target tumor-derived whole cancer cell therapeutic vaccine was developed based on an in vitro pre-treatment by photodynamic therapy (PDT) and was investigated using a poorly immunogenic tumor model. The vaccine was produced by incubating in vitro expanded mouse squamous cell carcinoma SCCVII cells for 1 h with photosensitizer benzoporphyrin derivative (BPD), then exposing to light (690 nm, 1 J/cm2) and finally to a lethal X-ray dose. Treatment of established subcutaneous SCCVII tumors growing in syngeneic C3H/HeN mice with 2x107 PDT-vaccine cells per mouse by a peritumoral injection produced a significant therapeutic effect, including growth retardation, regression and cures. Tumor specificity of this PDT-generated vaccine was demonstrated by its ineffectiveness when prepared from a mismatched tumor cell line. Vaccine cells retrieved from the treatment site at 1 h postinjection were intermixed with dendritic cells (DC), exhibited heat shock protein 70 on their surface, and were opsonized by complement C3. Tumor-draining lymph nodes treated by the PDT-vaccine contained dramatically increased numbers of DC as well as B and T lymphocytes (with enlarged memory phenotype fraction in the latter), while high levels of surface-bound C3 were detectable on DC and to a lesser extent on B cells. The PDT-vaccine produced no therapeutic benefit against tumors growing in C3-deficient hosts. It is suggested that surface expression of heat shock proteins and complement opsonization are the two unique features of PDT-treated cells securing avid immune recognition of vaccinated tumor and the development of a strong and effective antitumor adaptive immune response.
*Note: Secondary antibodies (FITC-anti-IgY and FITC-Chicken anti-Rat IgG) used in this publication were supplied by Gallus Immunotech Inc.