IFITM3 and lymphopenia: Furthermore, concentrations of chemokines including the lymphocyte-attracting chemokines CCL5 and CXCL10 within the spleens of Ifitm3–/– mice were elevated as compared with concentrations detected in WT controls (Supplemental Figure 2C), indicating that tissue lymphopenia was probably not due to impaired chemokine-mediated cellular recruitment.