Extracts of lung cancer cells reveal antitumour antibodies in sera of patients with lung cancer.

The objective of the present study was to reveal antitumour antibodies in sera of patients with small cell lung cancer (SCLC). The antibodies in sera of patients with SCLC and other tumours were detected by immunoblotting with whole extracts of SCLC cells as the antigen source. Sera of patients with various pulmonological disorders, irradiated during the liquidation of consequences of the Chernobyl nuclear power plant incident (a high-risk group in lung cancer), were also analysed. The present authors' found that SCLC sera contain a set (pattern) of antitumour antibodies which are rarely detected in sera of patients with cancers different from SCLC and very rarely, if ever, present in sera of healthy individuals. The sensitivity and the specificity of the pattern are equal to 80% and 91%, correspondingly. In the high-risk group in lung cancer, the frequencies of the antibodies are somewhat lower than the corresponding values in SCLC sera, but significantly larger than those in healthy sera. The findings of the present study create a basis for clinical application of the antitumour antibodies described.

Peroxiredoxin VI in human respiratory system.

Peroxiredoxins (Prxs) constitute a novel family of antioxidant proteins, which specifically prevent enzymes from metal-catalyzed oxidation. The localization of a member of the mono-cystein subfamily of Prxs, Prx VI in human respiratory system and its antioxidant properties were investigated. By immunoblotting, the Prx VI was found to be present in human respiratory epithelium. Immunostaining with rabbit polyclonal antibody raised against the Prx VI revealed that the said protein was present in apical areas and mucus of all respiratory airways from trachea to bronchioles. Immunodepletion of the Prx VI profoundly decreased the antioxidant activity of the respiratory epithelium extract.

Low titre autoantibodies against recoverin in sera of patients with small cell lung cancer but without a loss of vision.

To date, many authors have described the presence of autoantibodies against various neuronal proteins, paraneoplastic antigens (PNA), in a serum of patients with different kinds of malignant tumors located outside the nervous system. These autoantibodies may cross-react with the corresponding PNA or their epitopes present in neurons and thus initiate the development of a variety of neurological disorders, paraneoplastic syndromes (PNS), even though the primary tumor and its metastases have not invaded the nervous system. Cancer-associated retinopathy (CAR) is a rare ocular PNS induced by autoantibodies against several retinal antigens, one of which is a photoreceptor calcium-binding protein, recoverin. Only several CAR patients with a few kinds of cancer (endothelial carcinoma, breast cancer, epithelial ovarian carcinoma) have so far been found to contain autoantibodies against recoverin in their sera. As for lung cancer, the majority of CAR cases mediated by anti-recoverin autoantibodies have been revealed in patients with the most malignant lung cancer, small cell lung carcinoma (SCLC), and only one similar case has been described for a patient with non-small lung carcinoma. The common feature of all these anti-recoverin-positive patients, irrespective of the type of cancer, is the presence of both the CAR syndrome and high titres (as a rule, more than 1:1000) of the underlying autoantibodies in their serum. In this study, we have used recombinant myristoylated recoverin to screen serum samples of 50 patients with SCLC by Western blot and revealed 5 individuals with low titres of anti-recoverin antibodies, who have no manifestation of a loss of vision. To our knowledge, this is the first report on the presence of low titre autoantibodies against recoverin in a serum of patients with cancer, but without visual dysfunction.