An enzyme-linked immunoadsorbent assay, using nitrocellulose discs as solid phase and small sample volumes (50 microliter), was developed for the measurement of antibodies. This was used to screen CSF samples for autoantibodies against tissue components. Extracts from a selection of tissues from both "normal" and MS patients and from 3 glial cell lines were made in phosphate-buffered saline; in the case of neural and lymphoid samples the remaining particulate materials were subsequently solubilised with octylglucoside. The saline-soluble components were screened against CSF samples from MS patients (18), patients with other neurological disorders (10), and matched orthopaedic patients but no differences were found among the 3 groups. However, when the detergent-soluble components were screened a significant (at the P less than or equal to 0.01 level) elevation of reactivity towards brain was found in 6/16 MS patients and 2/12 patients with other neurological diseases when compared to their controls.