الملخص
@#【Objective】 To find out the possible marker for early warning or therapeutic target of severe dengue disease ,we studied B cell responses during natural dengue virus(DENV)infection and their association with disease severity.【Methods】Sixty-two cases and their blood samples were collected from the patients hospitalized during September to December in 2014 and three groups were designated as mild dengue(DF,n=33),severe dengue(SD,n=29)and control group(Control ,n=6). Multicolor flow cytometrywas used to analyze the dynamic changes of B cells and plasmablasts in the peripheral blood of patients during the acute phase and the critical phase. The plasmablasts in a succession of samplesfrom the same infected patients (including 3 mild and 3 severe cases) were further analyzed. We also observed the changes of B cells and their subsets ,including naive B cells ,memory B cells and plasmablasts,during primary and secondary infections. 【Results】 The expansion of B cells in the severe group was significantly higher than that in the mild group(P=0.013),especially on day 5 and day 6 after the symptom onset(P = 0.017 and 0.002,respectively). Compared with those in the control group,the plasmablasts in the mild and severe groups showed significant proliferation(P=0.011 and 0.032,respectively),but no statistical difference was observed between these two groups. The analysis of the serial blood samples showed that the plasmablasts,in mild cases,peaked on day 7 and 8 and returned to baseline on day 10,whereas in the severe group,peaked on day 7 to 9,and still existed at a certain rate after day 10. In mild dengue group,more proliferative B cells,less naive B cells and memory B cells were found in secondary infection than in primary infection(P = 0.028,0.010 and 0.037,respectively),but plasmablasts revealed no difference. In severe dengue group, only naïve B cells significantly decreased in secondary infection (P = 0.018). 【Conclusion】 B cell responses between mild and severe dengue after DENV- 1 infection present different trends. The significant proliferation of B cells in the early stage of the disease and the persistent existence of plasmablasts may be related to the severity of the dengue disease.