The expression of a cerebellar degeneration-associated neural antigen in human tumor line cells

We examined the expression of the paraneoplastic cerebellar degeneration-associated autoantigen (PCD-AA) protein in human tumor lines of different origins by using an immunoaffinity-purified antibody from a patient with paraneoplastic cerebellar degeneration (PCD) and uterine adenocarcinoma. Immunocytochemical studies revealed that this antigen is expressed in the cytoplasm of two different uterine carcinoma lines and the tumor lines of neural origin as well as in the cytoplasm of a normal skin fibroblast line. By immunoblot analysis, we detected a 52-kd antigen identical to the PCD-AA protein in all the cell lines studied, including a colon adenocarcinoma line, a small-cell lung carcinoma line, and a squamous cell lung carcinoma line. These results indicate that the PCD-AA protein is expressed in a wide range of tumor cells. In this respect, this antigen is distinguishable from the cerebellar degeneration-related--34 antigen, of which expression is confined to tumor lines of neuroectodermal origin and not detected in colon, breast, or ovarian carcinoma lines derived from patients without PCD. These findings suggest the variability of the immune response to antigens in PCD.