Cerebrospinal fluid interleukin 1 like activity during chronic relapsing experimental allergic encephalomyelitis.

Cerebrospinal fluid (CSF) and plasma samples were taken from strain 13 guinea pigs in various stages of chronic relapsing experimental allergic encephalomyelitis (CREAE). The samples were assayed for interleukin 1 (IL-1) in the C3H/Hej mouse thymocyte assay. After removal of inhibitors, IL-1 was detectable in low amounts in plasma (5 U/ml) throughout the course of the disease but was raised in the acute phase (12 U/ml). CSF IL-1 was, however, only present in low amounts (6 U/ml) during the acute phase but was elevated (18 U/ml) during the chronic stages of CREAE. During the relapse phase levels of IL-1 correlated with the total leucocyte count in the CSF. On gel filtration of CSF, IL-1 activity eluted at approximately 15 kD and could not be attributed to leakage of plasma IL-1 during CSF puncture or IL-2 activity.