Abstracts

Abstract presented at 5th Annual Conference on Vaccine Research - Baltimore, MD May 6-8, 2002

Immunostimulatory actions of SGN-00101 and the separation of these effects from Lipopolysaccharide.

Rowse G., Chu N.R., Wiebe E., Recktenwald A., Mizzen L., Boux H. and *Siegel M.I.

Stressgen Biotechnologies, Victoria British Columbia, CANADA. And *Collegeville, PA.

Immunization with SGN-00101, an Hsp fusion protein comprised of Mycobacterium bovis BCG Hsp65 linked to HPV16 E7, results in eradication of HPV E7 expressing cells in both preclinical models and human phase II clinical trials. Effective treatment with SGN-00101 requires activation of CD8+ve T cells. Since SGN-00101 is active without adjuvant, we wished to determine if HspE7 could stimulate the release of proinflammatory cytokines from cells of the innate immune system. THP-1 cells were stimulated with LPS, SGN-00101 or it’s component parts. For desensitization studies, cells were stimulated with LPS or SGN-00101, washed and then restimulated. For serum dependence studies, THP-1 cells were stimulated with SGN-00101 or LPS in 10% or 1% FCS. TNFa production was assessed by ELISA.

HspE7, but not Hsp65, E7 (or the admixture) induced the release of TNFa from THP-1 cells. While SGN-00101 was able to elicit TNFa release from THP-1 cells cultured in low serum containing media, LPS did not elicit TNFa under these conditions. Pretreatment with SGN-00101 desensitized the THP-1 cells to restimulation with either LPS or SGN-00101, while LPS pretreatment resulted in complete desensitization to restimulation with LPS, but only partial desensitization to SGN-00101. These results demonstrate that SGN-00101 is able to stimulate cells of the monocyte/macrophage lineage to secrete proinflamatory cytokines such as TNFa. Further, actions of SGN-00101 on THP-1 cells cannot be solely attributed to LPS as the stimulatory properties of SGN-00101 can be differentiated from those of LPS.