Predictive value of serum interleukin-6 level in influenza virus-associated encephalopathy.
OBJECTIVE
In Japan, >200 children with influenza virus-associated encephalopathy were reported in 1999 and the mortality rate was high. The levels of tumor necrosis factor-alpha (TNFalpha) and interleukin-6 (IL-6) in both CSF and serum were significantly increased in severe cases. The authors found a correlation between elevated serum cytokine levels and mortality and neurologic morbidity.


METHODS
TNFalpha, IL-6, soluble tumor necrosis factor receptor 1 (sTNF-R1), interferon-gamma (IFNgamma), and IL-2 were measured by the ELISA method in sera from six children with encephalopathy before and during therapy, and in six age-matched controls with influenza type A virus infection.


RESULTS
The increases in the serum TNFalpha, IL-6, and sTNF-R1 levels were statistically significant at the onset of symptoms before therapy, but the IL-6 level was most useful for diagnosis. The serum IL-6 levels were >6,000 pg/mL in children with brain stem dysfunction, about 150 pg/mL in children without brain stem dysfunction, and <80 pg/mL in controls. The time course of the serum IL-6 level also reflected the clinical condition. Once the serum IL-6 level was increased to >15,000 pg/mL, none of the children survived. The lower the maximal serum IL-6 level, the milder the CNS sequelae.


CONCLUSIONS
The serum IL-6 level may be the most useful indicator for the diagnosis and the clinical severity of influenza virus-associated encephalopathy.
Aiba
H
H
Department of Pediatric Neurology, Shizuoka Children's Hospital, Shizuoka, Japan. haiba@jun.ncvc.go.jp
Mochizuki
M
M
Kimura
M
M
Hojo
H
H
D001927:Brain Diseases / Q000097:blood* / Q000209:etiology*; D002648:Child; D002675:Child, Preschool; D016207:Cytokines / Q000097:blood / Q000134:cerebrospinal fluid; D005260:Female; D006801:Humans; D007223:Infant; D007251:Influenza, Human / Q000150:complications*; D015850:Interleukin-6 / Q000097:blood* / Q000134:cerebrospinal fluid; D008297:Male; D011237:Predictive Value of Tests; D011379:Prognosis; D013997:Time Factors
D016207:Cytokines; D015850:Interleukin-6