Presence of antibodies against retinoblastoma tumor suppressor protein in patients with lung cancer

Retinoblastoma (RB) protein and antibody against RB protein in sera from 45 lung cancer patients and 30 healthy volunteers were examined using bacterially synthesized glutathione S-transferase (GST) RB fusion protein and immunoblot analysis. RB protein was not detected in sera from any individuals with lung cancer or in any healthy volunteers. Sera from 6 patients, including 4 with non-small cell carcinoma and 2 with small cell carcinoma, reacted to a GST-RB fusion protein but not with a GST protein. Sera from 30 normal volunteers reacted to neither GST-RB fusion protein nor GST protein. The backgrounds such as age, gender, performance status, histology, stage, smoking history, and prior treatment were not significantly different between the patients with and without anti-RB antibodies. This is the first report describing the presence of anti-RB antibody in patients with malignant tumors. Further studies are needed to establish clinical significance for anti-RB antibody.