Objective To detect the levels of tumor necrosis factor (TNF)-a,interleukin (IL)-1β,IL-2,1L-6,IL-8,1L-10,IL-12 and interferon (IFN)-α in the serum and cerebrospinal fluid of the patients with epidemic encephalitis B,and to investigate the roles in pathogenesis of epidemic encephalitis B.Methods Approximately of 2 mL serum and 2 mL cerebrospinal fluid from 24 patients with epidemic encephalitis B during acute phase were collected,and 2 mL serum from 20 healthy controls were collected.The levels of eytokines in serum and cerebrospinal fluid were detected by enzyme linked immunosorbent assay (ELISA).Means of multi-sample were compared by analysis of variance and means of two-sample were compared by t test.Results The levels of TNF-α,IL-1β,IL-6,IL-8,IL-10 and IFN-α in eerebrospinal fluid were (24.5±6.6),(7.8±2.4),(16.0±5.7),(17.6±4.8),(130.2±33.6) and (45.2±10.8) ng/L,respectively,and in serum were (25.3±11.2),(7.1±3.2),(14.5±6.2),(16.0±6.5),(82.0±27.8) and (42.5±16.2) ng/L,respectively.The levels of TNF-α,IL-1β,IL-6,IL-8,IL-10 and IFN-α in serum and cerebrospinal fluid from patients with epidemic encephalitis B were all higher than those in serum of healthy controls [(12.7±7.9),(2.6±1.0),(6.2±2.2),(9.6±3.3),(71.4±12.8) and (30.0±14.0) ng/L;F value was 14.10,29.46,23.38,14.78,32.59,7.52;all P＜0.01];while the levels of IL-2 and IL-12 were not increased significantly.The levels of IL-1β,IL-6,IL-8,IL-10,IL-12 and IFN-α in cerebrospinal fluid were higher than those in serum,while the levels of TNF-± and IL-2 in cerebrospinal fluid were lower than those in serum.The levels of IL-6 and IL-8 in cerebrospinal fluid from patients with severe type of epidemic encephalitis B were (18.8±5.4) ng/L and (20.7±2.7) ng/L,and were higher than those with common type [(12.1±3.0) and (13.3±3.3) ng/L;t=3.50,t=5.96;P＜0.05],while the levels of IL-2 in serum and in cerebrospinal fluid from patients with severe type were lower than those with common type. Conclusions Oversecretions of TNF-α,IL-1β,IL-6,IL-8,IL-10 and IFN-a are involved in the inflammatory damage of epidemic encephalitis B,while under-secretions of IL 2 and ILl2 may be involved in cellular immune responses.