Regulation of HLA-DR antigen in monocytes from colorectal cancer patients by in vitro treatment with human recombinant interferon-gamma

During the immune response, a great number of cytokines that modulate the f unction of mononuclear phagocytes are produced. Since interferons are one o f the most important cytokines, the aim of this study was to evaluate the e xpression of HLA-DR antigen after an 18-h culture with human recombinant in terferon-gamma (hr/FN-gamma) on freshly isolated peripheral blood monocytes from 16 colorectal cancer patients and 16 healthy donors, using an indirec t immunofluorescence method. The results obtained showed that there was a d ecreased percentage of HLA-DR+ monocytes in the colorectal cancer patents ( 51 +/- 3%, p <0.01) compared with the healthy donors (77 +/- 2%). Treatment for 18 h with hr/FN-gamma increased the percentages of monocytes expressin g HLA-DR: 71 3% for the cancer patients and 84 +/- 2% for the healthy donor s (p <0.01 and <0.001, respectively). Our results demonstrate that after in vitro treatment with hr/FN-gamma, functionally altered monocytes from colo rectal cancer patients can reach major histocompatibility complex II antige n expression values similar to those of healthy donors, thus improving the host's cellular immune response against the tumor.