Canarypox vaccines induce antigen-specific human gamma delta T cells capable of interferon-gamma production

Induction of human gamma delta T cells was investigated in subjects who wer e vaccinated with live recombinant canarypox virus expressing human immunod eficiency virus (HIV) proteins or soluble MN rgp120. Both canarypox and rgp 120 induced antigen-specific lymphoproliferative and interferon (IFN)-gamma responses. However, only canarypox vaccination induced increased gamma del ta T cell responses detectable after secondary in vitro expansion (P < .02) . These enhanced <gamma>delta T cell responses were specific for canarypox but not HIV antigens. Canarypox-specific gamma delta T cells were predomina ntly V gamma9(+) and produced intracellular and secreted IFN-gamma. gamma d elta T cell lines generated from canarypox vaccinees responded to canarypox antigens but not to mycobacterial antigens shown previously to induce baci lle Calmette-Guerin-specific gamma delta T cells. Furthermore, canarypox va ccinations were associated with significantly higher NK cell expansions (P = .02). Increased IFN-gamma production by gamma delta T and NK cells could enhance the induction of protective type 1 memory immunity. Thus, stimulati on of gamma delta T cells might be an important feature of live vaccines.