Little is known about the role of mannan-binding lectin (MBL) in adaptive immune responses although it is believed to be of importance in innate immunity. The interaction of MBL with Raji cells, THP1/CD14 cells, Jurket cells and human red blood cells (HRBCs) has been investigated by ELISA, and the characteristics of MBL binding to Raji cells by FACS. The results showed that MBL could bind to Raji cells, THP1/CD14 cells and Jurket cells except HRBCs, and the binding was dose-dependent. Furthermore, the binding of MBL to Raji cells was evident in a Ca²⁺-dependent manner, which was partially inhibited by some saccharides (mannose, glucose, or N-acetylglucosamine), C1q and anti-C1qR mAb. Similarly, it was also incompletely inhibited by recombinant human MBL carbohydrate recognition domains (rhMBL-CRD) protein and recombinant human MBL collagen-like region (rhMBL-CLR) protein, respectively, but completely inhibited by both. These data indicated that Raji cells express Ca²⁺-dependent and sugar-sensitive CLR-specific and CRD-specific MBL receptors, of which, the former was also shared with C1q. Further investigation showed that MBL could significantly inhibit Raji cell proliferation directly at higher concentrations (10～50 mg/L) in a dose-dependent manner, suggesting that MBL might also play certain roles in adaptive immune responses.