Thymic MHC induces basal open-CD3 in WT thymocytes in vivo. Background, basal, and stimulated samples were prepared from B6 WT or B6 Abb−/− β2m−/− thymocytes to establish the amounts of open-CD3 using the CD3-PD assay. Amounts of open-CD3 relative to either the CD3-PD assay background or basal conditions were calculated for both types of thymocytes as in Fig. 2. Additionally, percent maximum (2C11 stimulation = 100%) was calculated to facilitate the comparison of basal open-CD3 observed from each thymocyte type. A, The measurements of open-CD3 found in B6 WT and Abb−/− β2m−/− mice from one representative experiment are shown. B and C, Values of basal open-CD3 as a percent maximum of 2C11 stimulation (B) and open-CD3 induction achieved by 2C11stimulation over basal (C) are plotted for five independent experiments. The mean ± SE is displayed representing the amount of open-CD3 found in thymocytes from each mouse type. Paired t tests were run to calculate p values.