The effectiveness of toxic oxygen metabolites in killing the yeast form of (the form that occurs in host tissues) was studied with a fluorescence method . The two isolates studied were similar in susceptibility and HO alone was lethal with an LD50 of 15–25 mM. The addition of halide (5 x 10 M) augmented the lethality of HO and in that setting HO was 90% lethal at 5 x 10 M. Killing was most effective in the presence of peroxidase, when only 5 x 10 M HO (a concentration attainable by phagocytes) was required for a 95% kill. Kinetic studies revealed that toxic concentrations of HO alone or of the HO-halide-peroxidase (PPH) system produced significant killing in 1 min; killing was maximal in 15 min. The PPH system was the more rapid in action. The dependence of the PPH killing system on HO was demonstrated by an absence of killing in the presence of catalase. The susceptibility of to HO and the PPH system appeared different in some respects from that noted for other dimorphic fungal pathogens. These studies suggest that toxic oxygen metabolites are important in host defence against .


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error