VARIATION IN INTERFERON-GAMMA RESPONSES TO COXIELLA-BURNETII ANTIGENSWITH LYMPHOCYTES FROM VACCINATED OR NATURALLY INFECTED SUBJECTS

Previous work in our laboratory has shown that lymphocytes from person s vaccinated with a formalin-inactivated Phase I Q fever vaccine (Q-Va x CSL Ltd) show a mitogenic response to Coxiella burnetii antigens. Th e mitogenic response is the sum of that from various subsets of CD4(+) , T helper cells, CD8(+). T cells and probably B cells. It does not di stinguish between T helper cell responses leading to formation of inte rferon-gamma (IFN-gamma)-a cytokine responsible for clearing intracell ular infection with C. burnetii organisms-and responses of other T cel l subsets which may produce disease-enhancing cytokines. The present s tudy analyses (i) the capacity of Q-Vax to induce T cell sensitization which leads to IFN-gamma responses on antigen stimulation, and (ii) t he immunomodulatory, (down-regulatory) effects of the Phase I lipopoly saccharide (LPS) of the organism, which interacts with monocyte/macrop hages to limit IL-2 production and production of IFN-gamma by sensitiz ed T lymphocytes.