The analysis of peri-tumor necrosis following the subcutaneous implantation of autologous tumor cells transfected with an episome transcribing an antisense insulin-like growth factor 1 RNA in a glioblastoma multiforme subject.

A subject inflicted with glioblastoma multiforme who received partial tumor resection and radiotherapy was recruited for an ex vivo gene therapy protocol using irradiated autologous tumor cells that had been engineered to suppress the expression of insulin-like growth factor I as the tumor vaccine. After subcutaneous injection for 8 weeks, the subject developed peri-tumor necrosis with mass effect. The authors wondered whether this event could have resulted from the tumor vaccine. The tissue section bordering the necrotic tumor tissue to the viable normal tissue was examined for nature of any infiltrated cells and their activities. Lymphocytes, macrophages, and a small number of neutrophils diffused into the necrotic tumor tissue were found. The infiltrated lymphocytes consisted of both CD4+ and CD8+ T cells. The functional activity of these lymphocytes was demonstrated by the active production of interferon y and tumor necrosis factor alpha based on the respective immunofluorescent staining localized to these cells. This finding is compatible with the proposed mechanism underlying the tumor vaccination. However, the contribution of radiation treatment to this event cannot be clearly ruled out.

The observation of immunosuppressor(s) derived from cultured tumor cells and its partial neutralization with OK-432.

Malignant tumors such as brain tumors have been reported to be associated with immunosuppression caused by certain tumor-secreted cytokines. The reversion of tumor-derived immunosuppression has not been described. The use of OK-432, an immunomodulatory agent prepared from Su-strain of Streptococcus pyogenes A3, to activate peripheral blood mononuclear cells from a patient with glioblastoma multiforme has demonstrated a sharp rise in proliferative response. This proliferative response was compromised in the presence of living and irradiated autogeneic cancer cells. The conditioned media from cultured cells of glioblastoma multiforme, astrocytoma, and cholangiocarcinoma were tested for immunosuppressive ability. We found that conditioned media from 3 of 4 cases of glioblastoma, all 3 cases of astrocytoma, and 1 case of cholangiocarcinoma exhibited immunosuppressive activity toward the proliferative response of allogeneic peripheral blood mononuclear cells to phytohemagglutinin. This is the first report that cholangiocarcinoma produces soluble immunosuppressor(s). Our finding suggested that soluble substance(s) as well as direct cell-cell contact between tumor cells and mononuclear cells play roles in the observed tumor-derived immunosuppression.