DEVELOPMENT OF CYTOSTATIC EFFECT OF MONOCLONAL ANTIBODIES TO THE PROTEINS PRAME

Introduction. PRAME protein is a promising target for cancer immunotherapy. PRAME is not expressed in normal tissues, but active in number of the tumor types. We have developed the mouse monoclonal antibodies 5D3F2 and 6H8F12 against PRAME epitopes. Aim. To determine the effects provided by the monoclonal antibodies 5D3F2 and 6H8F12 against the cells with different levels of PRAME gene expression. Materials and methods. We used different cell lines: NOMO-1 and WI-38 with low levels of expression PRAME; THP-1 with intermediate level of PRAME expression; K562 and WI-38-PRAME with high level of PRAME expression. We incubated these cell lines in the presence of monoclonal antibodies 5D3F2 and 6H8F12. The final concentration of monoclonal antibodies in culture varied from 6 pg/ml to 120 mcg/ml. The live cells were counted at the 24, 48 and 72 hours after incubation. The number of dead cells was evaluated by the MTT-test after 24 hours. Results. Cell growth rate is significanely decreased during incubation with monoclonal antibodies. This effect is correlated with increase of monoclonal antibody concentrations (Pearson coefficient 0,67;p = 0,0219). K562 growth rate was much less compared to the THP-1’s rate (p = 0,0061), NOMO-1 (p = 0,0005) and WI-38 (p = 0,0002) in the presence of the same amount of monoclonal antibody 6H8F12. K562 cell growth rate was lower than the WI-38-PRAME’s rate (p = 0,0027), despite the comparable level of PRAME expression. Effects of monoclonal antibody 5D3F2 and 6H8F12 were similar (p = 0,3946). According to the MTT-test, the comparable number of death cells in K562 and WI-38-PRAME was observed (p = 0,8405). Under the same conditions the amount of death cells in THP-1 was smaller than K562 (p = 0,6335). To compare with K562, fewer cells died in NOMO-1 and WI-38 (p = 0,0026 and p = 0,0005, respectively). Conclusion. It was shown that monoclonal antibody 5D3F2 and 6H8F12 exhibit a significant cytotoxic effect against PRAME-express-ing cells. In case of higher levels of PRAME expression the cytotoxic effect was stronger.