Objective： To inwvetigate the expression of MAGE-A3 mRNA in tissue samples derived from lung cancers and to discuss the possibility of using MAGE-A3 antigens as a new peptide vaccine for inunotherapy for lung cancers. Methods： Tumor tissue samples of lung cancers and paired non-tumor tissues of the lung were obtaimed from 31 lung cancer patients. Total RNA was extracted and cDNA was synthesized. Nested polymernse chain reaction amplification using MAGE-A3 specific primer was performed to detect the expression of MAGE-A3. The 10 clones of 5 samples of MAGE-A3 mRNA positive PCR products were DNA sequenced by using DNAs sequencer （PE-377）. Results： Of 31 lung cancers, 26 （83.9%） expressed MACE-A3 mRNA. The expression of MAGE-A3 gene was not detectable in the adjacent lung tissues. The DNA sequencing confirmed that the target gene fragment in all 5 samples of PCR products was MACE-A3 cDNA. Point nmtations occurred in 4 samples （8 clones） detected （C^2773→T^2773; G^2807→A^2807） resulting in alternation of amino acid residue in one position （E^143→K）. Conclusion： （1） The MAGE-A3 gene was expressed exclusively in tumor tissues of the patients with lung cancer in China. This tumor rejection antigen may have potential to be used as a new peptide vaccine for immunotherapy for lung eancers. （2） There are two point mutations of MAGE-A3 gene sequence in some Chinese lung cancer patients.
