Autoantibodies against the Ca(2+)-binding protein recoverin in blood sera of patients with various oncological diseases.

In cancer, the retinal Ca(2+)-binding protein recoverin is a paraneoplastic antigen, the aberrant expression of which is capable of triggering the appearance of specific autoantibodies in the serum of patients with malignant tumors and the subsequent development of a paraneoplastic syndrome, cancer-associated retinopathy (CAR). The frequency of serum autoantibodies against recoverin (AAR), earlier determined at a rate of 15-20% in lung cancer, is much higher than the frequency of CAR syndrome, which is approximately 1%. In the present study, we estimated for the first time the frequencies of serum AAR in patients with various types of malignancies other than lung cancer. Patient biospecimens were collected to analyze for the presence of AAR. Additionally, various cell lines were cultivated and analyses were performed using Western blotting and RT-PCR. Results showed that in all cases tested, the AAR frequencies did not exceed 10%. Five AAR-positive patients with various types of cancer were available for ophthalmological investigation and only one of these patients had CAR syndrome. This result is consistent with the conclusion made in our previous studies of lung cancer that serum AAR do not necessarily trigger the development of CAR syndrome.