Reactivity of circulating antineuronal antibodies (CANA) on peripheral nervous system structures.

The appearance of circulating antineuronal antibodies (CANA) in patients with malignant tumors has been correlated with the occurrence of paraneoplastic neurological syndromes. However, the effect of CANA on the peripheral nervous system is poorly understood. The reactivity of sera from CANA-positive and -negative patients were investigated on cryostat sections of peripheral nerves and skeletal muscle, and on nerve tease-fiber preparations. Only CANA-positive sera showed staining of Schwann cell nuclei on cryostat sections, whereas nerve tease-fiber preparations and sections of skeletal muscle remained negative. Positive direct immunofluorescence of small cell lung cancer (SCLS) cells was confined to CANA-positive patients only. These findings suggest the existence of a common antigen between SCLC and Schwann cells.