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One of the cardinal questions in tumor immunology is the identification of antigenic structures in human tumors that are recognized by host immune system. A powerful new methodology for identifying human tumor antigens eliciting humoral immune response is SEREX (serological identification of antigen by recombinant cDNA expression cloning). Here, by using this method, a recombinant cDNA expression library from lung cancer was analysed and several new tumor antigens were isolated. Using the lambda-ZAP vector, cDNA expression library was constructed from lung cancer tissues of three patients including a moderately differentiated lung adenocarcinoma, a highly differentiated lung squamous cell carcinoma and a moderately differentiated lung adeno-squamous carcinoma. The primary library consisted of 0.8 x 10(6) recombinants. 33 positive clones encoding antigen genes were obtained after immunoscreening, and the nucleotide sequences of cDNA inserts were determined and analysed with DNASIS and BLAST softwares in EMBL and GenBank. These antigen genes included known genes, such as MAGE (melanoma antigen gene), vitiligo-associated protein VIT-1, fibronectin, Na-K-ATPase et al and unknown genes or ESTs. To characterize expression profile of these genes, antibodies in sera from 48 lung cancer patients and 48 health donors were assayed with three antigens (L-8, L-19, L-51) to screen specific and relative serum markers for lung cancer. The results show that positive rates in lung cancer patients are higher than in health donors. Our research indicates that some of these antigens may be related to lung cancer and may be valuable tumor markers in diagnosis of lung cancer.