Fig. 1. Analysis of MHC class II molecules in SaI/A^k cells. (A) Surface expression of I-A^k molecules on SaI, SaI/A^k and SaI/A^k tr cells was determined by FACS analysis. Binding of I-A^k mAb and the isotype control Ig (IgG_2b) is shown. (B) Peptide-associated MHC class II ß compact heterodimers (Cß), high-molecular-weight (HMW) complexes and free ß chains were detected by western blotting on total cell lysates from SaI, SaI/A^k and SaI/A^k tr cells. Lysates were incubated in Laemmli sample buffer for 30 minutes at room temperature (nb, lanes 1, 2) or for 10 minutes at 95°C (b, lanes 3 and 5). Samples were migrated on a 10% SDS-PAGE gel before transfer to a PVDF membrane and immunoblotting with 10.2.16 mAb.