CD4 and immune system disorder: In order to explore the role of TLR2 or TLR4 in the activation of CD4+ T cells by PHSML and to further elucidate the importance and significance of TLR2 or TLR4 in immune dysfunction due to hemorrhagic shock, immunomagnetic bead sorting methods were used to isolate and culture CD4+ T cells of different (WT, TLR2-/-, TLR4-/-) mice which stimulated with PHSML or NML, and expression of CD25 (IL-2R) upon activated CD4+ T cells was examined with flow cytometry (Figure 4).