Natural killer cells in dengue hemorrhagic fever/dengue shock syndrome.

Natural killer (NK) cell activity against K-562 target cells and HNK-1+ cell levels were serially determined in peripheral blood of 62 Thai children with dengue hemorrhagic fever/dengue shock syndrome aged 4-12 years and 59 age-matched normal controls. The studies were performed on febrile stage, 1st and 2nd day of subsidence of fever (shock stage), 3rd and 4th day of subsidence of fever (early convalescent stage) and once again on the late convalescent stage (approximately 14-18 days after subsidence of fever). The study revealed that during the course of disease the NK cell activity was not changed significantly from the normal controls. In contrast, the levels of HNK-1+ cells, which exhibited almost all NK and killer cell functional activities, were significantly decreased in the febrile and the shock stages and were normal in the early and late convalescent stages. The NK cell activity, on the per-cell basis, was significantly increased in the early disease stage when compared to that of the later period of the disease and of the normal controls. The study also revealed that patients with grade III of disease severity exhibited significantly more NK cell functional activities per cell than grade II on febrile stage and the first day of shock. These results suggest that natural killer cells were active in defense against dengue viral infection and might play some role in the pathogenesis of dengue hemorrhagic fever/dengue shock syndrome. Their functions might also determine the severity of the disease.

Kinetics of lymphocyte subpopulations in dengue hemorrhagic fever/dengue shock syndrome.

A kinetic study of lymphocyte subpopulations was performed in 61 dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) patients aged 8 months to 12 years and in 59 age-matched normal controls. There were 36 patients in grade 2 and 25 patients in grade 3 of the disease severity. The studies were performed on febrile stage, the day of subsidence of fever or shock stage, 3 subsequent days after subsidence of fever or shock, and once on the recovery stage (approximately 14-18 days after subsidence of fever or shock). The study revealed that the absolute total lymphocytes, CD3+, CD4+, CD8+ and HNK-1+ cells were decreased on febrile stage and their lowest values were noted on the first day of subsidence of fever or shock, while B1+ cells were in the normal range. Thereafter, all lymphocyte subpopulations were increased. The total lymphocytes, B1+ and CD8+ cells were rapidly increased and were above normal value on day 2 after subsidence of fever or shock (early convalescence), then gradually declined to the normal range. In contrast, CD3+, CD4+ and HNK-1+ cells were increased gradually and reached their normal values on day 2 after subsidence of fever or shock. The T4:T8 ratio began to reverse on the day of subsidence of fever or shock, reached its peak on day 2 after shock and returned to normal ratio rapidly thereafter. Thus, the absolute lymphopenia on the day of shock was due to the decrement or T cells (both CD4+ and CD8+ cells) and HNK-1+ cells.(ABSTRACT TRUNCATED AT 250 WORDS)