Objectives: In this preliminary study, the in vitro effect of C-Vx in human PBMCs and the in vivo effect of C-Vx in rats were investigated. Methods: The human part was analyzed in PBMCs isolated from healthy subjects. Apoptotic index, cytotoxic activity of CD8+ T and NK cells, and cell proliferation of CD3+ , CD4+, CD8+ T and NK cells in response to different doses of C-Vxwere investigated. Also the hematological and biochemical parameters of the rats administered subcutaneously in three different doses of C-Vx were monitored for 14-days. Results: Increased CD107a expression in response to C-Vx on NK cells but not on CD8+ T cells support the increasing of NK cell cytotoxicity. C-Vx alone was capable of triggering proliferation of T and NK cells. The PHA-induced proliferation of CD3+ and CD4+ T cells was diminished in response to C-Vx, while PHA-induced CD8+ T cell proliferation was up-regulated. PHA-triggered proliferation of total NK cells was enhanced with the existence of C-Vx.C-Vx was well tolerated in rats with no serious adverse effects or mortality (death) after 14-days of follow-up. Biochemicalparameters (creatinine, blood urea nitrogen, etc.) were not significantly different among treated and control groups. Thelevels of white blood cells and lymphocytes were increased up to two-folds in the C-Vx group (especially 0.25 ml/day) ascompared to the control group. Conclusion: Taken together, these preliminary findings support the immunomodulatory effects of C-Vx. But these findings should cautiously be evaluated due to the low numbers of subjects in both human and experimental arms.