FIGURE 6.

Depletion of plasma membrane cholesterol decreases MHC-II I-A/I-E interactions and MHC-II/tetraspanin interactions. A, LPS-activated DCs were either mock-treated or treated with MCD at 37 °C, washed in ice-cold HBSS, and lysed in ice-cold buffer containing 1% Brij-58. MHC-II molecules were immunoprecipitated (IP) using I-A- or I-E-specific mAb and analyzed by immunoblotting using the indicated antibodies. An aliquot of the cell lysate was also analyzed. B, amount of I-E, CD81, or CD9 bound to I-A in MCD-treated DCs was determined by densitometry and was expressed as a fraction of the total amount of I-A present in the anti-I-A immunoprecipitate. Similar analyses were performed with the anti-I-E immunoprecipitates. The mean ± S.D. from three independent experiments is shown, and the data are expressed as a percentage of the amount of binding to I-A or I-E observed in mock-treated cell (*, p < 0.05; **, p < 0.005).