Reactivity of WT and βTD mutant CD11b/CD18 with conformation-sensitive mAb 24. FACS analysis of the reactivity of mAb 24 with WT and mutant CD11b/CD18-expressing K562 cells. Level of CD11b/CD18 surface expression was analyzed using mAb IB4. Mean fluorescence intensity (MFI) values for mAb staining are shown in each panel from a representative experiment (1 of 3 performed), except that MFI of mAb 24 staining is shown after subtraction of the background mock fluorescence staining levels and after normalization to the IB4 expression values.