A second wave of monocyte expansion may contribute to the severe dengue in 2014 outbreak in China (HUM4P.272)

The 2014 dengue outbreak, the largest one in the last ten years in China, resulted in 13,800 hospitalized patients and more than 300 severe dengue cases in Guangzhou. Both of the viral strain and the host immune background may contribute to severe dengue. Here we report the monocyte response in dengue fever (DF) and severe dengue (SD) during the acute infection of seven dengue patients (DF n=4 and SD n=3) using multiparameter flow-cytometry with a panel of 9-surface markers. We also compared dengue specific IgG, IgM and NS1 in serum at the same time points for each patient. Six of the seven patients were diagnosed as secondary DENV1 infection, while one DF diagnosed as primary DENV1 infection. NS1 was nearly cleared in all patients when the serum IgG and IgM reached the high level at day 8-10 from the onset of fever. Obvious monocyte expansion was observed in both of DF and SD groups, frequently companied with the expansion of CD14++CD16+ subset. But the pattern of the response in the two groups was different at the recovery phase. The monocyte expansion in DF group maintained at a high level at day 7-10. Interestingly, the SD group underwent a second wave of monocyte expansion, in parallel with clinical course, starting from day 7 to day 10, especially the CD16+CD64+ monocyte subset. The characteristics of monocyte responses in DF and SD groups will advance our understanding of human dengue pathogenesis and may implicate the potential targets for early therapy.