Expression of HLA class II MHC molecules in single transfected RM3 cell lines, as determined by HLA locus specific monoclonal antibodies. Expression was evaluated by flow cytometry using anti-DR (Panel a), -DP (Panel b), and –DQ (Panel c) antibodies (LB3.1, B7/21, and SPVL3, respectively). As a positive control, HLA Class I expression was evaluated using the anti-Class I antibody, W6/32 (Panel d). Black: LG2 EBV cell line (positive control); red: HLA DRB3*02:02 transfected RM3 line RRB3.02.2; green: HLA DQB1*06:02 transfected RM3 line RQ0602.3; blue: HLA DPB1*04:01 transfected RM3 line RP0401.2.