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 pa tients with different kinds of malignant tumors located outside the nervous system. These autoantibodies may cross-react with the corresponding PNA or their epitops present in neurons and thus initiate the development of a va riety of neurological disorders, paraneoplastic syndromes (PNS), even thoug h the primary tumor and its metastases have not invaded the nervous system. Cancer-associated retinopathy (CAR) is a rare ocular PNS induced by autoan tibodies against several retinal antigens, one of which is a photoreceptor calcium-binding protein, recoverin. Only several CAR patients with a few ki nds of cancer (endothelial carcinoma, breast cancer, epithelial ovarian car cinoma) have so far been found to contain autoantibodies against recoverin in their sera. As for lung cancer, the majority of CAR cases mediated by an ti-recoverin autoantibodies have been revealed in patients with the most ma lignant lung cancer, small cell lung carcinoma (SCLC), and only one similar case has been described for a patient with non-small lung carcinoma. The c ommon feature of all these anti-recoverin-positive patients, irrespective o f the type of cancer, is the presence of both the CAR syndrome and high tit res (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 man ifestation 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. (C) 2001 Elsevier Sc ience Ireland Ltd. All rights reserved.