DIFFERENCES IN OXIDANT RELEASE BY HUMAN POLYMORPHONUCLEAR LEUKOCYTES PRODUCED BY STIMULATION WITH DIFFERENT PHASES OF COCCIDIOIDES-IMMITIS

Human polymorphonuclear leukocytes (PMNL) inhibit growth of arthroconi dia and young spherules but not mature spherules of Coccidioides immit is. To evaluate these differences, oxidants were measured when PMNL we re exposed to C. immitis or other particulate stimuli. Concentrations of arthroconidia, young spherules, mature spherules, and Candida glabr ata were adjusted to result in equivalent superoxide release. Hydrogen peroxide and hypochlorous acid were stimulated by arthroconidia or yo ung spherules but were undetectable after exposure to mature spherules . Levels of catalase in mature spherules were too low to account for t he low levels of hydrogen peroxide and hypochlorous acid. When mature spherules were added to arthroconidia or zymosan, stimulation of hydro gen peroxide and hypochlorous acid occurred. The results suggest that mature spherules stimulate superoxide release but interfere with hydro gen peroxide and hypochlorous acid production. The lower levels of the se antimicrobial oxidants may contribute to resistance of C. immitis t o human PMNL.