AIM:To clone mouse anti-human gastric cancer mAb(3H11) variable genes and to construct 3H11 human-mouse chimeric antibody.METHODS: The entire VH and VL genes of anti-gastric cancer mAb 3H11 were cloned by RT-PCR method from 3H11 hybridoma cells, using 5' primers for leader sequences. The 3H11 VL gene was then inserted into human-mouse chimeric light chain expression vector and transfected into murine Sp2/0 myeloma cells.RESULTS: DNA sequence analysis indicated that the cloned genes included the whole leader sequences and the mature Ig variable region encoding sequences. After gene transfection, transient expression of chimeric light chain protein was detected.CONCLUSION: DNA sequences and transient expression indicated that the cloned gene was functional. This work laid basis for constructing 3H11 human mouse chimeric antibody in the future.