Biochemical analysis of HLA class I subunits expression in breast cancer tissues

The expression of HLA class 1 alpha-chain and beta(2)-m subunits was studied at the protein level by a semiquantitative Western blot (WB) approach, in 25 primary breast rumors. The results indicated three pathways of alterations defined comparing the tumor WB gel band with the corresponding PBL gel band: (i) high downregulation pattern (the tumor WE gel band was less than or equal to 50% relative to the PBL band), which was found in 44% and 36% of tumors for alpha-chain and beta(2)-m, respectively; (ii) low downregulation pattern (the tumor gel band was between 51% and 75%), which was found in 24% and 20% of tumors for alpha-chain and beta(2)-m, respectively; and (iii) absent downregulation pattern (the tumor gel band was >75%), which was found in 32% and 44% of tumors for alpha-chain and beta(2)-m, respectively. The concordance rate with immunohistochemistry (IHC) performed on the same tissue samples was 72% for alpha-chain and 64% for beta(2)-m This study shows that the use of a semiquantitative WE technique ran well define the levels of HLA class I antigens in an autologous setting allowing the biochemical analysis of HLA class I downregulation directly in solid tumor tissues. In addition, the WE technique can be a valuable tool to objectively support the IHC method. (C) American Society for Histocompatibility and Immunogenetics, 2000. Published by Elsevier Science Inc.