Figure 3.

Coexpression of R88A, D109, or R115A mutant LAG-3 molecules with wtLAG-3 molecules prevents MHC class II Daudi cells from binding to COS-7 cell transfectants. DNA amounts used for transfection were 10 μg/ml for wtLAG-3 (wt) and the negative control (GAL), and 40 μg/ml for mutants (A). Class II binding was determined by cpm counting in a cell–cell adhesion assay using ⁵¹Cr-labeled Daudi cells. B shows the inhibition of Daudi cell binding as a function of the amount of R88A, D109E, or R115A DNA transfected. wtLAG-3 DNA (10 μg/ml) and various amounts of mutant DNA (DNA ratio mutant/wt shown in abscissa) were mixed, and pCDM8 DNA was added to maintain the total amount of transfected DNA at 50 μg/ml.