title: Semi-allogeneic vaccines and tumor-induced immune tolerance.
abstract: Experimental results from studies with inbred mice and their syngeneic tumors indicated that the inoculation of semi-allogeneic cell hybrids (derived from the fusion between syngeneic tumor cells and an allogeneic cell line) protects the animal host from a subsequent lethal challenge with unmodified syngeneic tumor cells. Semi-allogeneic somatic cell hybrids were generated by the fusion of EL-4 T lymphoma cells (H-2b) and BALB/c-derived renal adenocarcinoma RAG cells (H-2d). Cell hybrids were injected intra-peritoneally (i.p.) in C57BL/6 mice (H-2b) before challenging the mice with a tumorigenic dose of EL-4 cells. Semi-allogeneic tumor cell hybrids could not form a tumor in the animal host because they expressed allogeneic determinants (H-2d) and were rejected as a transplant. However, they conferred protection against a tumorigenic challenge of EL-4 cells compared to control mice that were mock-vaccinated with i.p.-injected phosphate-buffered saline (PBS) and in which EL-4 lymphomas grew rapidly to a large size in the peritoneal cavity. Screening of spleen-derived RNA by means of focused microarray technology showed up-regulation of genes involved in the Th-1-type immune response and in the activation of dendritic antigen-presenting cells (APC). The results of our studies confirm the role of APC in mediating the immune protection induced by semi-allogeneic vaccines by activating a Th-1 response; these studies also reveal that semi-allogeneic vaccines are able to interfere with or even block the tumor-mediated induction of immune tolerance, a key mechanism underlying the suppression of anti-tumor immunity in the immune competent host.
authors.affiliation: Department of Radiation Oncology, Medical University of South Carolina, Charleston, SC 29425, USA. yujin@musc.edu
authors.forename: Jin
authors.initials: J
authors.lastname: Yu
authors.forename: Mark S
authors.initials: MS
authors.lastname: Kindy
authors.forename: Sebastiano
authors.initials: S
authors.lastname: Gattoni-Celli
mesh_terms: D000818:Animals; D002460:Cell Line; D017635:Clonal Anergy; D005786:Gene Expression Regulation; D006801:Humans; D006822:Hybrid Cells / Q000276:immunology*; D007108:Immune Tolerance / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D015996:Survival Rate; D018417:Th1 Cells / Q000276:immunology; D014612:Vaccines / Q000276:immunology*
chemical_list: D014612:Vaccines