IgE in the cerebrospinal fluid.

The level of IgE in the cerebrospinal fluid (CSF) was determined by particle counting immunoassay. With a limit of sensitivity of 0.2 IU/ml, this immunoglobulin was detected neither in CSF of non-neurological patients (n = 27) nor of patients with sciatica (n = 13). IgE was present in samples from some patients with either multiple sclerosis (MS) or various infections of the central nervous system. In these cases, an IgE index [CSF IgE/serum IgE: CSF albumin/serum albumin] was calculated as 0.29 (SD 0.12). This value is not abnormal as the mean IgG and monomeric IgA indices are 0.45 and 0.34, respectively. Therefore, the IgE detected in most of the CSF samples was not locally produced. However, most patients with tuberculous meningitis had clearly an increased IgE index suggesting a local biosynthesis, but we failed to detect any IgE antibody activity against purified protein derivatives.