Inflammatory cells infiltrating human colorectal carcinomas express HLA class II but not B7-1 and B7-2 costimulatory molecules of the T-cell activation

Lab Invest. 1996 May;74(5):975-83.


Colon cancer cells express potentially immunogenic proteins but are not rejected by the immune system. To induce an effective immune response, antigenic peptides have to be presented to T lymphocytes by professional antigen-presenting cells in association with HLA class II molecules. Antigen-presenting cells also have to express B7 family molecules, B7-1 and B7-2, which deliver the costimulatory signals that are required to prevent T cell anergy. We studied B7-1 and B7-2 expression by the antigen-presenting cells that infiltrate colorectal cancer stroma. In 25 samples of colorectal carcinomas, a panel of monoclonal antibodies was used to label macrophages, dendritic cells, and T lymphocytes that infiltrate the tumor stroma and the morphologically normal distant mucosa. The expression of HLA class II and B7 molecules involved in T-cell activation was studied using specific monoclonal antibodies. Biopsy pieces from two patients with active Crohn's disease were used as controls. All of the samples were heavily infiltrated by macrophages and/or dendritic cells that strongly expressed HLA class II molecules. In contrast, antibodies to B7-1 and/or B7-2 stained no cells in 16 of the 25 samples of colorectal tumors and less than 1% of the inflammatory cells that infiltrated tumor stroma of the other nine tumor samples. B7 molecules were also poorly expressed by rare cells in the lamina propria of the morphologically normal colorectal mucosa. In contrast, many inflammatory cells that infiltrated the two Crohn's disease samples strongly expressed B7-1 and B7-2, especially in the granulomas. We conclude that most HLA class II+ inflammatory cells that infiltrate colorectal cancers do not express the B7-1 and B7-2 costimulatory molecules. This defect may contribute to the failure of the immune system to recognize tumor cells as antigenic.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenocarcinoma / immunology
  • Adenocarcinoma / pathology
  • Antibodies, Monoclonal
  • Antigen-Presenting Cells / immunology*
  • Antigens, CD / analysis*
  • B7-1 Antigen / analysis*
  • B7-2 Antigen
  • Colorectal Neoplasms / immunology*
  • Colorectal Neoplasms / pathology
  • Crohn Disease / immunology
  • Crohn Disease / pathology
  • Dendritic Cells / immunology
  • Histocompatibility Antigens Class II / analysis*
  • Humans
  • Immunohistochemistry
  • Lymphocyte Activation
  • Macrophages / immunology
  • Membrane Glycoproteins / analysis*
  • Neoplasm Staging
  • T-Lymphocytes / immunology*


  • Antibodies, Monoclonal
  • Antigens, CD
  • B7-1 Antigen
  • B7-2 Antigen
  • CD86 protein, human
  • Histocompatibility Antigens Class II
  • Membrane Glycoproteins