PITFALLS IN THE DIAGNOSIS OF AUTOANTIBODIES ASSOCIATED WITH PARANEOPLASTIC NEUROLOGIC DISEASE

We studied the sera of 15 patients with Sjogren's syndrome using the W estern blot technique for the presence of anti-Re and anti-Hu (type 1 antineuronal nuclear autoantibody [ANNA-1]). All sera reacted with Ro- 52 protein. Two of the Sjogren sera reacted with 38-kd bands on Wester n blots of rat cerebellar homogenate, resembling anti-Hu immuno-reacti vity. However, when reacted with purified human Purkinje cells or puri fied recombinant HuD protein, none of the sera immunoreacted with the Hu antigens. We recommend the use of either a recombinant Hu protein o r the combination of immunohistochemistry and Western blot of purified human neuronal preparations to identify paraneoplastic antibodies. Th is approach will prevent the unnecessary workup for suspected lung can cer.