Activation by interferon-  of expression of ICAM-1 and MHC class II antigens in tumour cells from colorectal carcinomas

Abstract

Aims-To determine whether lack ofMHC class II antigen and intercellular adhesion molecule-i (ICAM-1) expression in some tumours is due to the inability of the tumour cells to respond to the cytokine interferon-y (IFN-y), an important activator of these surface molecules. Methods-Cells from 40 colorectal tumours which did not constitutively express class II MHC antigens or ICAM-l were kept in short term culture after disaggregation for a few days to two weeks without significant loss of viability. These were treated with IFN-y. Expression of class II MHC antigens and ICAM-1 was determined using immunohistological techniques. Results-There was clear induction in vitro of both MHC class II antigens and ICAM-1 in cells from eight ofthe tumours, with between 50 and 80% of the tumour cells in the cultures staining positively. The staining was apparent within 24 hours, appeared maximal at about three days, and declined thereafter. There were no obvious differences in cell morphology or viability between the cultures which were inducible and those which were not, nor were there obvious differences between the tumours from which they were derived. Conclusions-Expression of MHC class II antigens and ICAM-l may be induced by IFN-y in a small proportion of colorectal tumours which do not constitutively express these antigens, showing that only a minority of tumours are capable of responding to this cytokine.

Induction of intercellular adhesion molecule 1 and class II histocompatibility antigens in colorectal tumour cells expressing activated ras oncogene

“…These were amplified using the primers listed in table 1. ras codon 12113 PCR products were generated using the following cycle: one minute at 95°C, 30 seconds at 55°C, one minute at 72°C for 32 cycles, and then five minutes at 72°C. The 100,l reaction mixture was made up of the following: 10 [tl Taq buffer (500 mM KCl, 100 mM Tris/HCl (pH9 0), 1% Triton X-100) (Promega), 2-5 mM MgCl2, 80 ng DNA, 0-2 mM of each dNTP, 50 pmoles of each primer, and 2-5 units of Taq polymerase (Promega). ras codon 61 PCR products were generated using incubations for one minute at 95°C, three minutes at 63°C for 32 cycles and then three minutes at 72°C.…”