Abstract: Objective To prepare monoclonal antibodies against human FL molecule and analysis of their biological characteristics. Methods The BALB/c mice were immunized with the transfected cell line L929/FL that expressed membrane FL. The splenocytes from the immunized mice were fused with myeloma cell line SP2/0，and then the hybridoma cells were screened with immunostaing and FCM. The isotype of the monoclonal antibody identified by rapid isotyping analysis, and the FL expression profile on tumor cell lines was analyzed by indirect immunofluorescence with mAb 3E5. To analysis the biological function of mAb 3E5, we added the 3E5 to the RPMI1640 medium containing FL protein to culture THP-1 cells. Results a hybridoma cell line named 3E5 was obtained, which had the property of secreting anti-human FL monoclonal antibody continuously and steadily. Fast-strip method analysis displayed that these mAbs belong to mouse IgGl，K. The mAb 3E5 could recognize FL molecules on different cell lines. FL protein could enhance the proliferation of THP-1, and it could be neutralized by 3E5 mAb. Conclusion Our study established a neutralized anti-human FL mAb which may prove a useful tool for studying the biological fUnction of FL.

Key words: FL, Hybriboma, Monoclonal antibody