Figure 2.

The effect of siplizumab (A), Alemtuzumab (B), and rabbit anti-thymocyte globulin (rATG) (C) on T cell proliferation in allogeneic mixed lymphocyte reaction (MLR). T cell proliferation was measured at baseline (day 0) and on days 1, 2, 4, and 7. Data is displayed as the mean of all data points (N = 9 donor pairs) ± SD. T cells were identified as CD3⁺ CD56⁻ lymphocytes. Proliferation was measured via violet proliferation dye 450 (VPD450; VPD450low = proliferated). Data were analyzed using two-way ANOVA followed by Dunnett’s multiple comparison test with untreated controls (no antibody) serving as the comparison data set (*p < 0.05, **p < 0.01, ****p < 0.0001). (A) Siplizumab did not affect T cell proliferation up to day 4. After 7 days of allogeneic MLR, siplizumab significantly inhibited T cell proliferation at 0.01 µg/ml (p = 0.0358), 0.1, 1, and 10 µg/ml (p < 0.0001). (B) Alemtuzumab did induce notable changes in T cell proliferation. (C) rATG significantly increased T cell proliferation after 4 days of allogeneic MLR at 0.01 µg/ml (p = 0.0019) and 1 µg/ml (p = 0.0150) and significantly decreased T cell proliferation after 7 days of allogeneic MLR at 0.01 µg/ml (p = 0.0252). (D) Representative T cell proliferation histograms from MLRs treated with no antibody, 10 µg/ml siplizumab, 10 µg/ml Alemtuzumab, and 10 µg/ml rATG.