The Effect Of Human Peripheral Blood Monocyte-derived Dendritic Cells In Trichosporon Asahii Infection

Objective Trichosporon asahii is an important conditional pathogenic fungus, which can cause deep infection, leading to disseminated trichosporosis in immunocompromised populations, and infection carries a mortality rate in excess of 77%. Recent years, the incidence of the disease significantly increased. Clinical failures with amphotericin B, fluconazole, and combinations of the two have been reported. So, having a better guidance on the immune response of T.asahii infection may provide a theoretical basis for further research of immunology effective treatment measures. In this study, we established a model of monocyte-derived dendritic cells infected by heat-inactivated T.asahii conidia for investigating the effects of T.asahii on the phenotypic and functional maturation of human peripheral blood monocyte-derived dendritic cells(DCs).Methods The monocyte-derived DCs of health donors were obtained by culture in vitro. DCs were incubated with different concentrations of heat-inactived T.asahii conidia in the experimental groups,(DCs:T.asahii=1:1,1:5,1:10),RPMI-1640 and lipopolysaccharide(LPS) stimulated groups were the blank or positive control groups, respectively. After 24 h of stimulation, the rate of phagocytosis was calculated by Wright Giemsa staining, the DCs maturation was analysed by using flow cytometry, the cytokines of IL-12 and IL-10 released into the supernatant were detected by double antibody sandwich enzyme-linked immunosorbent assay(ELISA). Moreover, the T.asahii pulsed DCs were generated and culture with T cells for 72 h, the proliferation of T lymphocyte were detected by MTT.Results 1. During 5 days culture,the morphology of DCs was significantly changed. On the fifth day, the cells had differentiated into typical DCs morphology with more dendrites and a larger size. At least 95% of the DCs population stained was positive for CD11 c. Cell viability was consistently > 95%. 2. At 30 min of co-incubation, DCs were surrounded by a great number of conidia, some conidia were bound to DC S and some were internalized, at 24 h of co-incubation, there was an increased number of condia been phagocytosed, the phagocytic rate were consistent with T.asahii conidia concentration, and significantly different between each groups(P<0.05). 3. After 24 h of co-incubation, the immunophenotypic expression of CD80, CD86, CD83 on DCs are increased comparing with the control group(P<0.05), which were consistent with T.asahii conidia concentration, but significantly lower than LPS group(P<0.05). 4. After 24 h of co-incubation, the IL-12,IL-10 leveles in cell culture supernatant are increased comparing with the control group(P<0.05), which were consistent with T.asahii conidia concentration, but significantly lower than LPS group(P<0.05). 5. After 72 h of co-incubation,the Stimulztion index of T lymphocytes were much higher than the control group(P<0.05), which were consistent with T.asahii conidia concentration, but significantly lower than LPS group(P<0.05).Conclusions 1. DCs has strong endocytosis ability to heat-inactived T.asahii conidia and plays an important role in the innate immune response;2. After stimulated by heat-inactived T.asahii conidia, the immunophentypic expression of CD80, CD86, CD83 is increased and the function of DCs is activated,which induce the adaptive immune response; 3. After stimulated by heat-inactived T.asahii conidia,the IL-12 secretion is increased, which may induce the Th1 immune response.