4-1BB and OX40 stimulation enhance T-cell responses to poxvirus vaccine.

2004 OCT 6 - (NewsRx.com & NewsRx.net) -- 4-1BB and OX40 stimulation enhance CD8 and CD4 T-cell responses to a DNA prime, poxvirus boost vaccine.

"4-1BB (CD137) is a tumor necrosis factor receptor (TNFR) family member, expressed primarily on CD8 T cells after activation. Signaling through 4-1BB has been reported to enhance CD8 T-cell expansion and to protect activated CD8 T cells from death, resulting in an enlarged memory population. Although stimulating 4-1BB has been shown to significantly improve the immune response to weak immunogens such as tumors, little is known about its effect on the CD8 T-cell response to a powerful viral vector such as vaccinia," scientists writing in the journal Immunology report.

"To test 4-1BB's ability to improve the murine CD8 T cell response to a DNA prime, poxvirus boost vaccine, similar to those used for human immunodeficiency virus and simian immunodeficiency virus vaccines, we administered 4-1BB agonist antibody at the time of the poxvirus boost," said Michael W. Munks at Oregon Health and Science University and collaborators in the U.S. "4-1BB stimulation increased the number of functional memory CD8 T cells by two- to four-fold. However, we saw a similar enhancement at the peak of the response and in the memory phase, thus we found no evidence in the context of virus infection that 4-1BB stimulation could increase the percentage of CD8 T cells that survive the acute activation phase to ...