IFN-γR1 and IFN-γR2 surface expression in malignant T cells. Surface expression of IFN-γR1 and IFN-γR2 in ST4 T cells evaluated by flow cytometry after 24-hour culture in the presence of complete medium (A-B), IGF-1 (100 ng/mL) (C-D) or anti–IGF-1R blocking mAb (10 μg/mL) (E-F), medium without serum (G-H) or medium without serum supplemented with IGF-1 (100 ng/mL) (I-J) using anti–IFN-γR1 γR99 (A,C,E,G,I) or anti–IFN-γR2 mAb (B,D,F,H,J). The histogram represents the expression of IFN-γR1 (left panels, gray histogram), IFN-γR2 (right panels, gray histogram), or background of mouse IgG1 negative control (white histogram) in the ST4 T-cell line in 1 representative experiment of 3 independently performed. Results in frame are expressed as percentage of positive cells calculated by subtracting the positivity of nonspecific fluorescence detected with isotype-matched control Ig from that obtained with specific fluorescence, and the mean of fluorescence intensity (MFI) is indicated.