This study identifies NY-ESO-1, a testicular antigen aberrantly expressed in human cancers, using autologous antibody screening. NY-ESO-1 is expressed in normal testis and ovary, but shows high-level expression in various cancers, including melanoma, breast cancer, bladder cancer, prostate cancer, and hepatocellular carcinoma. It encodes a protein of molecular weight 17,995 with no homology to any known protein. NY-ESO-1 belongs to a family of immunogenic testicular antigens that are aberrantly expressed in human cancers in a lineage-nonspecific manner. These antigens, initially detected by either cytotoxic T cells or antibodies, represent a pool of antigenic targets for cancer vaccination. The study used a method called SEREX (Serological Analysis of Recombinant cDNA Expression Libraries) to identify immunogenic tumor antigens. This method involves the use of tumor mRNA and autologous patient serum to screen cDNA expression libraries. The results showed that NY-ESO-1 is expressed in a variable proportion of various human cancers. RT-PCR and Northern blot analysis confirmed the expression of NY-ESO-1 in testis and certain cancers, but not in normal colon, kidney, liver, or brain. The expression of NY-ESO-1 in normal tissues was also evaluated, and it was found to be expressed in testis and ovary, but not in other normal tissues. The study also identified other testicular antigens, including NY-ESO-2, NY-ESO-3, NY-ESO-6, NY-ESO-4, NY-ESO-5, and NY-ESO-8. These antigens are expressed in various cancers and may serve as targets for cancer vaccination. The study highlights the importance of identifying immunogenic tumor antigens for cancer immunotherapy. The results suggest that NY-ESO-1 and other testicular antigens may be useful for developing cancer vaccines. The study also discusses the molecular characteristics of NY-ESO-1, including its potential N-myristoylation sites and phosphorylation sites, and its possible transmembrane domain. The study concludes that NY-ESO-1 is a promising candidate for cancer immunotherapy.This study identifies NY-ESO-1, a testicular antigen aberrantly expressed in human cancers, using autologous antibody screening. NY-ESO-1 is expressed in normal testis and ovary, but shows high-level expression in various cancers, including melanoma, breast cancer, bladder cancer, prostate cancer, and hepatocellular carcinoma. It encodes a protein of molecular weight 17,995 with no homology to any known protein. NY-ESO-1 belongs to a family of immunogenic testicular antigens that are aberrantly expressed in human cancers in a lineage-nonspecific manner. These antigens, initially detected by either cytotoxic T cells or antibodies, represent a pool of antigenic targets for cancer vaccination. The study used a method called SEREX (Serological Analysis of Recombinant cDNA Expression Libraries) to identify immunogenic tumor antigens. This method involves the use of tumor mRNA and autologous patient serum to screen cDNA expression libraries. The results showed that NY-ESO-1 is expressed in a variable proportion of various human cancers. RT-PCR and Northern blot analysis confirmed the expression of NY-ESO-1 in testis and certain cancers, but not in normal colon, kidney, liver, or brain. The expression of NY-ESO-1 in normal tissues was also evaluated, and it was found to be expressed in testis and ovary, but not in other normal tissues. The study also identified other testicular antigens, including NY-ESO-2, NY-ESO-3, NY-ESO-6, NY-ESO-4, NY-ESO-5, and NY-ESO-8. These antigens are expressed in various cancers and may serve as targets for cancer vaccination. The study highlights the importance of identifying immunogenic tumor antigens for cancer immunotherapy. The results suggest that NY-ESO-1 and other testicular antigens may be useful for developing cancer vaccines. The study also discusses the molecular characteristics of NY-ESO-1, including its potential N-myristoylation sites and phosphorylation sites, and its possible transmembrane domain. The study concludes that NY-ESO-1 is a promising candidate for cancer immunotherapy.