IL6 and herpes simplex encephalitis: These results are in contrast to HSVE patients with a mean IL-6 concentration in CSF of 315.5 pg/ml (range 1.77–552.9 pg/ml) and serum of 12.7 pg/ml (range 0.3–573.3 pg/ml) resulting in a mean ratio of 24.84, pointing at the CNS as IL-6 source (see Table 4).