Differential Desensitization to Type I Interferons Figure 3. Differential desensitization of human primary cells. (A) Human foreskin fibroblasts and (B) human T cells were either left untreated (na¨ıve) or primed for 8 hr. Cells were washed, maintained in medium without IFN for 16 hr and stimulated for 30 min with 10 and 100 pM of the indicated IFN. Cell lysates (30 mg) were analysed with the indicated Abs. (C) Human primary hepatocytes were left untreated (na¨ıve) or primed with 500 pM of IFN a2 or 30 nM of IFN l1 for 24 hr. Cells were washed, maintained in medium without IFN for 24 hr and stimulated for 30 min with the PLoS ONE | www.plosone.org 5 July 2011 | Volume 6 | Issue 7 | e22200