In vitro Inhibition of Human Melanoma Cells by Immunotoxin Luffin B-Ng76.

Luffin B, a plan single-chain ribosome inactivating protein, was purified from seeds of Luffa cylindrica by Blue Sepharose CL-6B affinity chromatography. An immunotoxin was constructed with luffin B and Ng76, a monoclonal antibody to human melanoma cell M(21). Luffin B-Ng76 showed 4 000-fold more cytotoxic to target melanoma cells than free luffin B. The IC(50) of luffin B-Ng76 for M(21) cells and non-target HeLa cells was 2.5x10(-11) mol/L and 3.0x10(-8) mol/L, respectively. The results suggest that luffin B is a new potent immunotoxin effector.