Characterization of the atypical lymphocyte in dengue hemorrhagic fever compared with dengue-like syndrome

Abstract

The blood samples from 49 DHF, 25 DF, and 26 DLS were used to demonstrate atypical lymphocyte count and cellular immune activation, and to evaluate the proportion of CD4+, CD8+, CD19+, CD69+, CD87+ and TDT+ cells during the acute phase of dengue illness, by flow cytometry. The statistical methods used were the ttest, ANOVA, Pearson’s correlation test and the receiver operating characteristic (ROC) curve. The results revealed that the mean number of total atypical lymphocytes was higher in patients with DHF (916.1±685.6 cells/µl) than in those with DLS (310.5±181.4 cells/µl, p<0.05), and patients with DF had higher atypical lymphocytes (876.2±801.9 cells/µl) than DLS (310.5±181.4 cells/µl, p<0.05), but there were no differences between counts in patients with DHF and DF. In a ROC plot of the atypical lymphocyte, the selected cut-off value was 10 because it gave good sensitivity and specificity (50% and 86%). The mean percentage of CD4+ T cells was significantly reduced in DHF patients, but not significantly different in DHF patients compared with DF and DLS patients. The mean absolute count of CD19+ B cells in DHF (615±577 cells/µl) and DF (478±369 cells/µl) was significantly higher than DLS (246±169 cells/µl, p<0.05). A CD19 count of e” 15% or 20% could distinguish DF/DHF from DLS, with a sensitivity of 69% and specificity of 50% if the CD19 was e” 15%, and a sensitivity of 49% and specificity of 85% if the CD19 was e” 20%. The atypical lymphocytes, CD19+ B lymphocytes and CD69+ lymphocytes had significant correlation coefficientsr=0.403 and –0.241, respectively. The atypical lymphocyte had a linear positive correlation with the CD19+ B lymphocyte and a negative correlation with the CD69+ lymphocyte, at á=0.01. The percent of cells expressing CD69 was more increased on CD8+ T cells than CD4+ T cells, and CD19+ B cells, respectively. However the absolute count of CD69 expressed on all lymphocytes was higher than the absolute count of CD69 on total B and T lymphocytes. The atypical lymphocyte cell could not be differentiated from the lymphocyte by morphology only, but perhaps from NK cells. Further studies are needed to elucidate the roles of NK cells in the pathogenesis of dengue viral infection.