DEPENDENT ANTIMICROBIAL ACTIVITY Assay for 1 - 1202 Generation

O u r pr ior observat ions wi th ac t iva ted mononuc lea r phagocytes have impl i ca ted oxygen in te rmedia tes as impor t an t effector molecules in bo th the in t race l lu la r destruct ion and the growth inhib i t ion of Toxoplasma gondii (1-3). Because this complex ox ida t ive in terac t ion m a y be m o d u l a t e d by the presence of endogenous scavengers wi th in e i ther the paras i te or host cell, we examined the roles of superoxide d ismutase (SOD)l , catalase, and g lu ta th ione peroxidase (GP). Together , these enzymes comprise a po ten t t r i ad of in t race l luar defense mechanisms against the toxici ty of superoxide anion (O2-) and hydrogen peroxide (H2Oz) (4). The i r ac t iv i ty has been invest igated in T. gondii and in various ma c ropha ge popula t ions , ob ta ined from in vivo and in vi tro envi ronments , that express different an t imic rob ia l behavior . O u r f indings demons t ra te tha t the levels of these three scavengers of oxygen in te rmedia tes vary from cell to cell du r ing cul t iva t ion , and that they can be corre la ted with the effectiveness of m a c r o p h a g e an t i t oxop la sma activity. In par t i cu la r , in t race l lu la r cata lase appears to p l ay an impor t an t m o d u l a t i n g role in mac rophage toxop la sma interact ion.