Figure 4

Modified one-way mixed leukocyte reaction (MLR) results at the lower responder cell concentration of 1.5 × 10⁶leukocytes (A, C) and at the higher responder cell concentration of 2.5 × 10⁶leukocytes (B, D), as measured by relative responder T-cell proliferation (A, B) and CFSE geometric mean fluorescence intensity (GMFI; C, D). Bars represent mean ± SD of n = 5. Superscript letters indicate significant differences between groups by ANCOVA, with horse as a covariate, followed by the Tukey test for multiple comparisons, P < 0.05. MHC-M, MHC-matched; MHC-MM, MHC-mismatched. MHC-mismatched MHC class II-negative MSCs caused significantly less responder T-cell proliferation compared with both the positive control of MHC-mismatched PBLs (MHC-MM MLR) and MHC-mismatched MHC class II-positive MSCs at both responder leukocyte concentrations (A, B). MHC-mismatched MHC class II-negative MSCs resulted in a significantly greater CFSE GMFI, indicative of fewer responder T-cell divisions, compared with MHC-mismatched MHC class II-positive cells at the higher responder leukocyte concentration (D).