Neutrophil oxidative metabolism and killing of P. brasiliensis after air pouch infection of susceptible and resistant mice

Fundacao Oswaldo Cruz, Rio de Janeiro, Brasil Abstract: The oxidative burst of polymorphonu-clear neutrophils (PMN) and their ability to inhibit Paracoccidioides brasiiensis growth was studied in susceptible (B1O.A) and resistant (A/i) mice. The cells were obtained after subcutaneous inoculation in air pouches, yielding highly pure PMN preparations; the number of cells was similar for both strains at 24 h and five times higher in the resistant strain at 15 days. The oxidative metabolism of these PMN was evaluated by the luminol and lucigen-enhanced chemiluminescence upon stimulation with PMA or killed P. brasiliensis (Pb). At 24 h of infection PMN from both strains showed similar responses. How-ever, at 15 days a great enhancement of the Pb-stimulated luminol-enhanced chemiluminescence was observed only in PMN from resistant mice. Such increase was markedly inhibited by the addition of catalase. Independent of the mouse strain or time of infection the lucigenin-enhanced chemiluininescence showed the same intensity. The lucigenin-enhanced chemiluminescence of PMN without stimuli from resistant mice did not change with the time of infec-tion, however, after 15 days of infection a signifi-candy lower chemiluminescence was detected with PMN from susceptible mice. At 15 days of infection the PMN from B1O.A were unable to kill P. brasil-iensis yeast cells in vitro. Because the lucigenin- and luminol-enhanced chemiluminescence detects, re-spectively, the 02 production and the myeloperoxi-dase/hydrogen peroxide halide system, the present data show parallels between deficiency in the produc-tion of oxygen-reactive species by PMN and lowe