TNF-alpha detection using a flow cytometric assay to determine cellular responses to anthrax vaccine.

This study describes a four-color flow cytometric assay that detects CD4+ T cell responses to the anthrax vaccine. Whole blood from seven volunteers who previously obtained the anthrax vaccine was inoculated in vitro with varying concentrations of the anthrax antigen. TNF-alpha and IFN-gamma production from memory CD4+ T cells were measured and compared to a control group who never received the anthrax vaccine. The optimal antigen concentration for TNF-alpha was determined to be around 7.5 microg/ml and IFN-gamma production was not detected. This assay will be used in future larger prospective studies to further evaluate the cellular immune responses induced by the anthrax vaccine.