Recoverin as a paraneoplastic antigen in lung cancer: the occurrence of anti-recoverin autoantibodies in sera and recoverin in tumors.

Using immunoblotting with recombinant recoverin as an antigen, we have examined 279 serum samples from individuals with small cell lung carcinoma (SCLC, 99 patients), non-small cell lung carcinoma (NSCLC, 44 patients), and non-malignant pulmonary disorders (86 patients) as well as sera from 50 healthy donors. Autoantibodies against recoverin (anti-Rc) were detected in sera from 15 patients with SCLC (15% of cases) and from 9 patients with NSCLC (about 20% of cases). Only two anti-Rc positive cases were detected in patients with non-malignant pulmonary disorders, while no such cases were found in healthy individuals. Immunohistochemical investigation of paraffin sections of 44 SCLC and 40 NSCLC tumors revealed recoverin-positive reaction in 30 SCLC (68%) and 34 NSCLC (85%) sections. Despite the high specificity (98%), the low sensitivity (less than 20%) does not allow serum anti-Rc to be considered as a valuable marker of lung cancer. However, taking into account the high occurrence of aberrant expression of recoverin in lung tumors, this PNA could be considered as a potential target for immunotherapy of lung cancer.