CD4 and Sepsis: In contrast, there was no difference in the frequency of CXCR4-expressing effector memory (TEM CD44HICD62LLO) CD4+ T cells in septic mice compared to sham mice (32% vs. 31.8%; p = 0.86; Fig 1F) suggesting that sepsis induces an upregulation of CXCR4 on less differentiated or antigen experienced CD4+ T cells.