Effect of gamma interferon on HLA class‐I and ‐II transcription and protein expression in human breast adenocarcinoma cell lines

The spontaneous expression of HLA class-I and class-II molecules in 5 human breast carcinoma cell lines, MCF-7, T47D, ZR75-I, HSL-53, MDA-MB 231, and their modulation during IFN-γ treatment, are reported. The expression of cell-surface determinants was examined by indirect immunofluorescence using monoclonal antibodies (MAbs) specific for HLA class-I and class-II (DR, DQ and DP) antigens. The biosynthesis and maturation of these molecules were analyzed by 2-dimensional gel electrophoresis analysis (2D-PAGE) of class I, DRα, β and invariant immunoprecipitates. Transcription was analyzed by Northern blot hybridization with HLA class-I and -II cDNA-specific probes. In all cell lines, more than 80% of cells expressed HLA class-I antigens at their surface. 2D-PAGE and mRNA studies showed a variable basal level of HLA class-I biosynthesis and transcription with a constant increase after 1,000 U/ml IFN-γ treatment. HLA class-II determinants were totally absent from the surface of MCF-7, MDA MB231, ZR75-I and T47D but they were detected in a small subpopulation of HSL-53 cells (DR 6%, DQ 6%, DP 20%). Spontaneous biosynthesis of HLA-DR molecules in immunoprecipitates analyzed by 2D-PAGE or transcripts in Northern blot were not detected in the 5 cell lines. Treatment with 1000 U/ml IFN-γ Induced or increased the expression of HLA class-II molecules in all cell lines but DQ expression was variable. While T47D, ZR75-I and HSL-53 increased their transcripts and antigen expression, MDA, MB231 and MCF-7 showed no DQ mRNA transcript. Biochemical analysis of the DR products revealed a classical α, β and invariant (Ii) chain pattern, but indicated a constant glycosylation defect in the invariant chain in all cell lines, associated with weak expression of the β chain and the presence of an extra spot of low molecular weight in the acidic part of the gel. Thus, post-transcriptional events did not appear to be totally controlled by IFN-γ in the different cell lines. These differences in DQ expression and glycosylation process in different breast cancer cells may be important in the activation of the immune response among different individuals.