To investigate the ability of HCV VLPs and E 8 Pam 2 Cys to cause activation of DCs, we measured the expression of surface MHC class II molecules following incubation with the various antigens. The results (Figure 2A) indicate that untreated DCs contained two populations of cells which were MHC class II low and MHC class II high , the latter comprising ,24% of the population analysed. While the distribution of these populations was not affected by exposure to HCV VLPs alone, incubation with HCV VLPs mixed with E 8 Pam 2 Cys caused a dramatic shift in the distribution of MHC class II expressing cells such that 83% of cells were MHC class II high . The upregulation of MHC class II expression on these cells were comparable to those cultured in the presence of LPS which is a potent DC maturation stimulus.