Figure 1. FR104 and CTLA4-Ig inhibit human T cell proliferation in vivo.

Fluorescent-labeled human PBMCs (5 × 10⁶) were adoptively transferred by i.p. injection on day 0 into immunodeficient mice. (A) CD28 expression on human T cells was measured 6 days later (n = 3). (B and C) Mice were treated on day 1 and day 3 with saline, PEG, FR104, or CTLA4-Ig i.v. (n = 3). Peritoneal cells were harvested on day 6 after adoptive transfer. FR104 and CTLA4-Ig significantly inhibited human T cell proliferation and activation in vivo. This assay was repeated 3 times using different human PBMC donors. Data are shown as mean ± SD. All data were analyzed by one-way ANOVA followed by Tukey’s multiple-comparisons test. *P < 0.01, **P < 0.001.