OBJECTIVETo study the major histocompatibility complex class II (MHC II) antigen and costimulatory molecules expression on the surface of breast cancer cells.

METHODSMHC II antigen and costimulatory molecule expression on five breast cancer cell lines including MCF-7, SK-BR-3, T47D, MDA-MB-435 and ZR-75-30 were detected through flow cytometery analysis, with their expression level compared with that of normal mammary cell line HBL-100.

RESULTSThe MHC II expression level of the five breast cancer cell lines were significantly different from that of HBL-100 (P < 0.05). MHC II antigen expression of MCF-7 cells which was about 20 percent of HBL-100 was the lowest. MDA-MB-435 and ZR-75-30 cell expression levels were twice as much as that of HBL-100, with the fluorescence intensity of MDA-MB-435 the highest of all cells. CD40 molecule expression on the surface of MDA-MB-435 cells was the lowest, which was nearly ten percent of that of MCF-7 and HBL-100 cells. CD80 and CD86 molecule expression showed no difference in MDA-MB-435 or HBL-100 cell (P > 0.05), and those of the other four breast cancer cells were lower than that of HBL-100 (P < 0.05).

CONCLUSIONMHC II antigen and costimulatory molecule expression on the surface of breast cancer cells is abnormal, with different molecule expression in different cells. Breast cancer cells can escape immune surveillance through abnormal molecule expression.