The relationship of antibody levels to the clinical spectrum of human neurocysticercosis. One hundred proven cases of cerebral cysticercosis were studied with an enzyme linked immunoassay (ELISA) employing cyst fluid as antigen, with a view to detecting specific antibodies in serum and cerebrospinal fluid (CSF). Antibody levels were correlated with the clinical presentation of the patients, the type and number of cysts detected on their brain scans, the anatomical position of these cysts and the presence of lymphocytes in the CSF. Patients could be divided into two distinct categories, one with low levels of antibody in the serum and absent antibody in the CSF, and the other with high levels in both the serum and the CSF. This differentiation matched the clinical presentation of a benign and a malignant group. Antibody levels could not be related to the type of cysts as observed on the brain scan, but depended on the anatomical position of the cyst, being lower if the cysts were confined to the cerebral cortex. A correlation of antibody levels with the number of cysts was only found in the benign group. 