Purkinje Cell Cytoplasmic Autoantibody Type 2 (PCA-2)

Neuron-restricted autoantibodies are important markers of neurological autoimmunity related to cancer. PCA-2 in 10 patients. Nine had mixed subacute neurological presentations. All 9 were smokers, and 8 had definite or probable lung cancer. One patient had no follow-up information. A 10th patient was among 58 with uncomplicated SCLC. PCA-2 binds to a cytoplasmic antigen in neurons and SCLC cells. Its immunostaining pattern in mouse tissues is distinct from that of the paraneoplastic autoantibodies PCA-1 and PCA-Tr. PCA-2 binds to cerebellar Purkinje somata and dendrites, neurons in internal granular layer and dentate nucleus, and neuronal elements in gut and kidney. Western blots of reduced/denatured cerebellar and SCLC proteins reveal a common antigenic band, of approximately 280 kd. PCA-2 is the seventh IgG neuronal autoantibody marker of paraneoplastic autoimmunity identifiable unambiguously by standardized immunofluorescence criteria.