studied the anti-tumor activities of a monoclonal anti-MUC1 antibody with oral squamous cell carcinoma (OSCC) and effects of membrane-bound complement regulatory proteins to anti-tumor activities. The OSCC cell line HSC4 was highly expressed of MUC1. Treatment of HSC4 cells with anti-MUC1 mAb C595 and fresh human serum resulted in deposition of C3 on HSC4 cells. C595 also enhanced complement-mediated lysis of HSC4 in the presence of fresh human serum. Because the level of C3 deposition and complement-mediated lysis of HSC4 cells caused by C595 was low, the effect of membrane-bound complement regulatory proteins (CRPs), such as CD46, CD55 and CD59 on inhibiting complement activation was investigated on HSC4 cells. All of CRPs were highly expressed on HSC4 cells. Then, when the complement-dependent cytotoxicity was compared treatment with C595 inhibiting of CD55 or CD59 by each functionally blocking mAb to C595 alone, a 2- to 3-fold increase in C-dependent cell lysis was observed, respectively. These results indicate that complement activation by immunotherapy to OSCC was inhibited by CRPs. The inhibition of CRPs may be an effective treatment of immunotherapy for OSCC.
View full abstract