Abstract: Objective: We found more inversion of CD4:CD8 ratio in volunteers and normal human. We tried to known whether there was earlier stage infection in the bodies.Methods: PBMC from healthy human volunteers were separated on Ficoll-Paque gradients. Lymphocytes were incubated with SEB or without SEB. The cells were stained with anti-CD4-FITC, anti CD8 PE, or anti-CD16-FITC and were analysed by flow cytometry. Results: the ratio of inversion in the volunteers and normal human was 64% Enhancing CD8⁺T cells were related to CD16 molecular expression （ P ＜ 0.05）. The results after SEB stimulating were showed that CD4⁺T cells in inversion of CD4:CD8 ratio were immune unresponsive T cells. Conclusion: enhancement of CD8 positive T cells was seem to relative to early stage of infection. Activating CD8⁺T cells might be suppression T cells, they inhibited responses of CD4⁺T cells.