Peripheral blood natural killer cells in Crimean-Congo hemorrhagic fever.

BACKGROUND The relationship of changes in the peripheral blood lymphocyte subgroups during Crimean-Congo hemorrhagic fever (CCHF) to prognosis has not been reported. OBJECTIVES To determine peripheral blood lymphocyte subgroups in CCHF patients at the time of diagnosis and relate these to clinical outcome. STUDY DESIGN Peripheral blood samples were obtained from the patients treated at the Karadeniz Technical University Hospital for CCHF in 2004. Lymphocyte subgroups were analyzed by flow cytometry on these samples and their association with patients' risk group (severe vs. non-severe) and mortality was recorded. RESULTS There were significantly more peripheral blood natural killer (NK) cells in severe risk CCHF patients than in non-severe risk group CCHF patients. A positive correlation was found between NK cell count and aspartate transferase (AST), alanine transferase (ALT) and activated partial thromboplastin times (aPTT). In addition, NK cell counts were observed to be higher in two patients who died. CONCLUSION Elevated NK cell counts may be a prognostic marker in CCHF patients.