A plant fermentation was carried out by Yeast and Lactobacilli against single cellular algae (f-Chlorella). These materials were proved by as safe in animal safety experiment. We sought to look into changes of immune-competent cells that commonly utilized f-Chlorella including after administration of immno-suppressed animals. The effects by f-Chlorella on the regurational effect to the host were measured. Our results showed that f-Chlorella regulated the level of lymphocytes, while conventional-Chlorella worked to adjust the level of granulocytes. In our clinical study with 20 healthy volunteers, granulocyte and lymphocyte ratio was obtained as neutral in the peripheral blood. In rodents, immune-compromised host as well as normal animal were prepared with cancer chemotherapeutic agent (Mytomycin-C), and then tried to rescue the immune-competent rebel. Our observations showed that both Chlorella derivatives regulated in number and functions. The effect was more prominent in f-Chlorella than that of conventional one. We discussed the significance and mechanism of f-Chlorella on the level of leukocyte subsets in number and function. These effects were considered to bring the potential elevation of antibody secreting cell by the localized heamolysis in gel method. We also proposed an idea that exhibited tonic effects were brought via activating the complement components in the serum. Moreover, we tried to access further to the anti-oxidative activities of this f-Chlorella. This modification brought to the significant lifted up for immune competent cells and anti-oxidative activity for phagocytic cells.