Phagocytosis and intracellular killing of yeasts by murine phagocytic cells

Objectives: The purpose of this study was to compare the phagocyte's ability to kill Candida albicans and phagocytosis by neutrophils and macrophages in two strains of mice. Methods: Live Candida albicans 3630 labeled with FITC were used for killing assay and fixed yeasts labeled with FITC for phagocytosis. Neutrophils were isolated from long-term bone marrow culture of CBA/CaH and BALB/c mice and macrophages were derived from short-term bone marrow culture conditioned with M-CSF. Two-colour flow cytometry was used to determine the killing and phagocytosing of yeasts. Results: The results demonstrated: 1. Killing of yeasts without opsonization by neutrophils from CBA/CaH mice (5.83±6%) was parallel to that (8.77±9%) of BALB/c mice (P>0.05), whereas macrophages killing of yeasts from CBA/CaH mice (9.89±4%) was lower than that of BALB/c mice (39.41±7%) (P<0.05); 2. Killings of yeasts opsonized with murine normal serum by neutrophils (6.6±3%) and macrophages (66.55±1%) from CBA/CaH mice were both depressed comparing with those of BALB/c mice (30.12±8% and 82.83±5%) (P<0.05); 3. Phagocytosis of yeasts without opsonization by neutrophils from CBA/CaH mice (96.5±2%) was higher than that of BALB/c mice (68.79±3%) (P<0.05), whereas phagocytosis of yeasts by macrophages from two inbred mice was equal (42.24±12% vs 31.74±4%) (P<0.05). Conclusions: 1. The neutrophils and macrophages from BALB/c mice have more efficiency intracellular killing of Candida albicans 3630 than from CBA/CaH mice. 2. The opsonisation of yeasts with normal mouse serum could improve the ability of killing for both neutrophils and macrophages from two strains of mice.