BackgroundCrimean–Congo hemorrhagic fever (CCHF) is a potentially fatal disease caused by a tick-borne virus from the Bunyaviridae family. Cytokines plays an important role in the pathogenesis of viral, bacterial, and immunologic diseases. This study aimed to investigate the role of TNF-alpha, IL-6, IL-10, and IFN-gamma levels in the severity of infection and clinical outcome of patients with CCHF.MethodsPatients with confirmed CCHF were divided into two groups (severe cases: Patients who exhibited hemorrhage during their hospital stay, and mild/moderate cases: Patients who displayed no hemorrhage during their hospital stay). Demographic characteristics, laboratory tests on admission of all patients with CCHF were investigated, and serum TNF-alpha, IL-6, IL-10, and IFN-gamma levels were measured.ResultsA total of 154 patients with confirmed CCHF were investigated. Forty-six (29.9%) of these patients were in the severe group. In patients with severe CCHF, significantly higher serum levels of TNF-alpha (68.2 ± 23.5; P = 0.008) and IL-6 (73.1 ± 41.6; P = 0.003) were detected, compared with cytokine levels in patients who mild/moderate CCHF (Table 1). No differences in serum IL-10 and IFN-gamma levels between patients who severe CCHF and those who mild/moderate CCHF were detected (P > 0.05).Table 1: Cytokine levels, demographic and laboratory characteristics in patients with severe and mild/moderate cases with CCHF.FeaturesSevere cases n = 46Mild/moderate cases n = 108 P-valueAge50.6 ± 20.349.8 ± 21.00.682Female gender, n (%)31 (67.4)63 (58,3)0.291 TNF- 68.2 ± 23.5 41.3 ± 17.4 0.008 IL-6 73.1 ± 41.6 38.0 ± 19.5 0.003 IL-106.32 ± 1.36.21 ± 1.40.753IFN-gamma145 ± 96126 ± 920.664WBC3286 ± 5,6022,275 ± 1,2860.280 PLT 53,564 ± 36,520 98,065 ± 42,768 0.001 CRP 3.2 ± 2.6 1.1 ± 1.4 0.005 ALT 521 ± 482 208 ± 320 0.044 AST 869 ± 1.182 256 ± 215 0.016 CPK 1,138 ± 970 676 ± 835 0.007 LDH 1,800 ± 1,254 589 ± 271 0.002 ConclusionCytokines, chemokines, and other inflammatory mediators function in a manner, acting on many different cell types to regulate the host’s immune response. When cytokines present in high concentrations, they might toxic or even lethal effects. In accordance with this view, we have detected increased serum TNF-alpha, IL-6 levels in the patients with severe CCHF.Disclosures All authors: No reported disclosures.