Fig. 1

U937 Minus cells, but not U937 Plus cells express HLA-II and CIITA. a HLA-I and HLA-II phenotyping of U937 Minus and U937 Plus cells was carried out by immunofluorescence and FACS analysis. Raji B cells were used as a positive control for both HLA-I and HLA-II expression. Histograms represent fluorescence profiles of the cells indicated on the left, incubated with specific anti HLA-I or HLA-II mAbs (solid line) or with FITC-conjugated F(ab)2 anti mouse antibody (dashed line). By using three mAbs each covering subgroups (DQ1, DQ2 and DQ3) of DQ molecules we found that U937 Minus cells are DQ2-positive. Mean fluorescence (mf) values are expressed in the abscissa as arbitrary units (au). b HLA-II DR and CIITA mRNAs expression in U937 Minus cells, U937 Plus cells and Raji B cells was assessed by qRT-PCR. The results of a representative experiment performed in triplicates are shown. CIITA and HLA-II DR mRNA levels are expressed as values relative to those of Minus cells set to 1. Raji B cells were used as a positive control for both CIITA and HLA-II DR mRNA expression. Unpaired two-tailed t test has been performed (****P < 0.0001; ***P = 0.0001). Error bars represent the standard deviation