HLA-DR ANTIGEN EXPRESSION ON COLORECTAL CARCINOMAS - INFLUENCE OF EXPRESSION BY IFN-GAMMA IN-SITU AND ITS ASSOCIATION WITH TUMOR PROGRESSION

The authors attempted to investigate the host's immune response agains t colorectal carcinoma through the expression of HLA-DR antigen on car cinoma cells (Ca) and on normal epithelia immediately adjacent to carc inoma (AN) in relation to tumour progression. The expression of HLA-DR antigen on Ca and on normal epithelial, both on AN and those 5-10 cm removed from the carcinoma (RN), were examined immunohistochemically. mRNAs of cytokines, IFN-gamma and TNF-alpha, were detected by reverse transcription-polymerase chain reaction (RT-PCR) in both carcinoma and remote normal tissues. The expression oi HLA-DR antigen on AN was sig nificantly increased compared with RN. Patients with rumours showing H LA-DR staining both in Ca and AN were in less advanced Dukes' stages ( Dukes' A or B) compared with those without the stain. Furthermore, the expression of HLA-DR antigen in normal mucosa coincided significantly with the existence of IFN-gamma mRNA. Detection in carcinoma tissues of IFN-gamma mRNA that leads to the induction of HLA-DR antigen on AN could be an indicator of a host's immune response to carcinoma. These in vivo observations might be clinically applicable to the prediction of patients' immune responsiveness to carcinomas.