Expression of an antigen in small cell lung carcinoma lines detected by antibodies from patients with paraneoplastic dorsal root ganglionpathy.

We have identified an autoantibody that reacts with a neuronal nucleoprotein in the serum of patients with small cell lung carcinoma (SCLC) and the paraneoplastic syndrome, subacute sensory neuronopathy (SSN). A similar antigen has been found in the tumor from one of these patients. To determine the distribution of this antigen, immunoblots of a homogenate from the SCLC of another patient with SSN, six SCLC cell lines from patients without SSN, five non-SCLC cell lines, and one ovarian carcinoma cell line were reacted with serum from five patients with SCLC and SSN. Control sera were obtained from two patients with SSN without cancer, two patients with SSN associated with tumors other than SCLC, two patients with paraneoplastic cerebellar degeneration, and five patients with SCLC but no SSN. The sera from all five patients with SCLC and SSN identified a Mr 35,000 to 40,000 antigen in neurons, in all of six SCLC cell lines and in the SCLC tumor homogenate. The antigen was not detected in other tumor cell lines. Control sera did not react with these bands, in either neurons or SCLC cell lines. Bound IgG was eluted from the blot of one SCLC cell line after reaction with SSN serum. Eluates from the Mr 35,000 to 40,000 area reacted with neuronal nuclei in the cerebral cortex by an immunoperoxidase technique; eluates from other areas of the blot were negative. These findings support the hypothesis that the autoantibody in SSN arises in reaction to an antigen shared between SCLC and neuronal nuclei.