Objective To study the expression of signaling lymphocytic activation molecule (SLAM)CD150 in peripheral blood mononuclear cells(PBMCs)isolated from adult non-responders to recombined yeast gene hepatitis B vaccine.Methods A total of 202 cases were recruited.All these subjects had been immunized with recombined yeast gene hepatitis B vaccine for more than one standard scheme in two years(from Sep 2007 to Dec 2009)and remained negative for hepatitis B markers(HBsAg,anti-HBs,HBeAg,anti-HBe and anti-HBc).After recruitment,all 202 subjects received another standard scheme(0,1 and 6 month)revaccination.The blood samples were collected 7 months later after the first injection of revaccination to detect anti-HBs titer.The PBMCs were isolated from 18 adult non-responders(anti-HBs titer<10 mIU/mL)and 18 adult responders(antiHBs titer≥100 mIU/mL).CD150 expression on cell surface was analyzed by flow cytometry.SAS package was used for t test and spearman rank correlation analysis.Results After rHBsAg stimulation,the percentage of PBMCs expressed CD150 was significantly higher in non-responders (39.20%±10.66%)than responders(23.73%±12.41%)(t=2.1947,P<0.05).The same trend was also observed in rHBsAg stimulated C133+CD4+T cells,but the difference was not statistically significant(49.64%±11.94%vs 37.73%±11.02%)(t=1. 7175,P>0.05).After phytohaemagglutinin (PHA)stimulation,the percentage of CD150-positive PBMCs was also significantly higher in non-responders (39.21%±7.37%)than responders(23.18%±12.68%)(t=2.2835,P<0.05).CD150 expressions in both PBMCs and CD3+CD4+T cells were negatively correlated with anti-HBs titer after rHBsAg stimulation (r=-0.726,P<0.05).Conclusion Activation of CD150 may contribute to the non-response to hepatitis B vaccine.