Fig. 5.

Selective association of CD9 with MHC II in DCs as compared with B blasts. (A) Expression of selected tetraspanin molecules on APCs. Green lines, B blasts; red lines, immature DC; blue lines, mature DC. (Left) CD81. (Right) CD9. (B) IF of DCs labeled with I-Ek (red) and the following: (Top) CD81 (green, permeabilized); (Middle) CD9 (green, permeabilized); and (Bottom) CD9 (green, live, nonpermeabilized labeling on ice). Boxed areas on merged right panels are shown at higher magnification in individual colors. Arrows indicate examples of partial CD9 and MHC II surface colocalization. Confocal images of a single plane are shown. (C) Immunoprecipitations and Western blotting for I-A were carried out as in Fig. 4A. CD9 IPs (lanes 1 and 2) as compared with CD81 IPs (lanes 3 and 4) from B blasts and DCs, respectively.