SMEZ-2 M1 does not stimulate T cell proliferation from human or murine immune cells. Human PBMCs (a), murine C57BL/6 (b), or humanized DR3-DQ2 (c) or DR4-DQ8 (d) transgenic splenocytes were cultured with graded doses of SMEZ-2 wild type (wt), M1, and DM for 3 days, and proliferation was quantified by uptake of tritiated thymidine over the final 16 h of the culture period. Murine data are the mean ± SD from 10 individual mice per figure combined from 5 independent experiments. Results for human PBMCs (mean ± SD from triplicate wells) from a single healthy donor are shown as a point of comparison.