Conjugation of interferon-gamma to antigen enhances its adjuvanticity.

Interferon-gamma (IFN-gamma) is an effective immunological adjuvant when mixed and injected with antigen, and previous work has shown that to be at its most effective IFN-gamma and antigen should contact the same antigen-presenting cells. The present study is an attempt to increase the adjuvanticity of IFN-gamma by ensuring that this happens through the use of an IFN-gamma-antigen conjugate. The use of biotinylated IFN-gamma, mixed with the antigen, avidin, significantly enhanced delayed-type hypersensitivity (DTH) responses to avidin, and caused a slight, but insignificant, increase in secondary antibody responses. Combined IFN-gamma-antigen molecules could provide a means of further enhancing vaccine immunogenicity.