Neural tissue hypersensitivity in psychiatric disorders with immunologic features.

The study population consisted of 1010 in patients and 81 control subjects. Patients suffering from schizophrenia, cerebral atrophy of unknown origin, dementia, depression, mental retardation, and ethanol-induced brain deterioration (alcoholics) were skin tested with 25 micrograms of S-100 protein and neuron-specific enolase isolated from fresh human brain. Evaluation of delayed skin hypersensitivity reactions at 24 hr revealed a high incidence of positive responses to S-100 protein: heavy alcoholism, 96.8%; depression, 94.1%; cerebral atrophy, 92.6%; dementia, 91.2%; schizophrenia, 87.7%; and mental retardation, 69.4%. The incidence of positive reactions to neuron-specific enolase in schizophrenics was 91.6%. Of 58 control subjects tested with S-100 protein, 6.8% were positive, whereas of 23 normal individuals tested with neuron-specific enolase, 6.4% developed mild skin reactions. These data suggest a close relationship between delayed hypersensitivity to neural tissue antigens and immunopsychiatric diseases, and they imply that cell-mediated immune mechanisms are involved in the pathogenesis of certain mental disorders.