Abstract: CHEN Qing*, ZENG Rong, SHEN Yong-nian, HU Su-quan, LI Min, LIU Wei-da. *Jiangsu Province Blood Center, Nanjing 210042, China Corresponding author: LI Min, Email: minli08@gmail.com 【Abstract】 Objective To investigate whether human neutrophils kill Candida albicans through recognition of insoluble β-glucan in cell walls of C. albicans （CaIG） by dectin-1, a C-type lectin receptor. Methods Neutrophils were obtained from peripheral blood of healthy human subjects and cultured in vitro. Real-time PCR was carried out to quantify the mRNA expressions of dectin-1 and Toll-like receptor 2 （TLR2） in neutrophils challenged with CaIG of 100 mg/L for 1, 6, and 24 hours. A Fluoro hydrogen peroxide （H2O2） detection kit was used to determine H2O2 levels in some neutrophils exposed to CaIG （100 mg/L） for 15 minutes, 2 hours, 6 hours, as well as in some neutrophils preincubated with laminarin （a dectin-1 inhibitor） of 100 mg/L and 50 mg/L for 30 minutes followed by challenge with CaIG of 100 mg/L for 2 hours. Colony forming units （CFUs） were counted after the incubation of C. albicans with neutrophils pretreated with laminarin of 100 mg/L and 50 mg/L for 30 minutes. Results The relative mRNA expression level of dectin-1 was 2.8195 ± 0.1669, 5.4859 ± 0.7244 and 3.6041 ± 0.5372 in neutrophils challenged with CaIG for 1, 6 and 24 hours, respectively, significantly higher than that in unchallenged neutrophils at these corresponding time points （all P < 0.01）. The level of H2O2 was （64.55 ± 15.67）, （290.34 ± 30.56）, and（208.54 ± 26.88） μmol/L respectively in neutrophils treated with CaIG for 15 minutes, 2 hours, and 6 hours respectively, compared to （22.05 ± 3.99） μmol/L in untreated neutrophils （all P < 0.01）. The pretreatment with laminarin of 100 and 50 mg/L attenuated the release of H2O2 in CaIG-treated neutrophils by 73% （（80.45 ± 22.41） μmol/L, P < 0.01） and 45% （（130.42 ± 44.55） μmol/L, P < 0.01）, respectively, compared with neutrophils treated with CaIG only. The fungicidal activity of neutrophils against C. albicans was also significantly inhibited by pretreatment with laminarin of 50 and 100 mg/L （both P < 0.01）. Conclusions Dectin-1 may be involved in the secretion of H2O2 as well as killing of C. albicans by human neutrophils, which may provide a preliminary evidence for adoptive transfer of neutrophils as an approach to the treatment of systemic C. albicans infection. 【Key words】 Candida albicans; Neutrophils; beta-Glucans; Lectins, c-type; Hydrogen peroxide