Irena Ruggiero

Tumour-cell-induced production of tumour necrosis factor by monocytes of gastric cancer patients receiving BCG immunotherapy

SummaryHuman peripheral blood monocytes cocultured with tumour cells were used as an in vitro model of in situ interactions between tumour-infiltrating macrophages and the tumour. Tumour cells stimulated de novo expression of the human tumour necrosis factor α (TNF) gene in monocytes and caused the release of TNF into the culture supernatant. A group of 14 patients with stage IVA gastric cancer receiving adjuvant chemotherapy (5-FU, Adriamycin, mitomycin C: FAM) or immunochemotherapy (BCG+FAM) was investigated for the ability of monocytes to produce TNF in vitro upon stimulation with tumour cells or purified protein derivative of tuberculin (PPD). Patients were followed at biweekly intervals, i.e. before each instillation of BCG epicutaneously over a period of 10 weeks. It was found that monocytes of some patients receiving BCG at the end of the observation period had an enhanced ability to produce TNF following stimulation with tumour cells. In contrast, such production was not substantially altered during the study period in patients on chemotherapy. PPD-induced TNF production was much weaker and was not significantly changed during this observation time. We infer that BCG immunotherapy may induce the subtle changes in some cancer patients that lead to an increased interaction between monocytes and tumour cells and result in enhanced production of cytokine(s) with antitumour properties.

The regulation of polyclonal immunoglobulin synthesis by FcR+ and FcR− monocyte subsets

FcR+ and FcR- monocyte subsets were added to the pokeweed mitogen (PWM) or Staphylococcus aureus Cowan I-stimulated cultures of peripheral blood mononuclear cells (PBMC) or to PBMC depleted of monocytes. The numbers of immunoglobulin-secreting cells (ISC) and cells with intracytoplasmic immunoglobulins (PC) were evaluated 6 days later. The addition of FcR- subset increased the number of ISC in cultures of PBMC stimulated with PWM and reconstituted the response of monocyte depleted PBMC. In contrast, FcR+ monocytes suppressed PWM-induced response and, when added in high dose, also that induced by S. aureus. The FcR+ monocytes suppressed the response by inhibition of immunoglobulin secretion but not the development of PC. This suggests that FcR+ monocytes may modulate humoral response by preferential inhibition of the final differentiation of B lymphocytes into ISC.

DEMONSTRATION OF INOS-MRNA AND INOS IN HUMAN MONOCYTES STIMULATED WITH CANCER CELLS IN VITRO

Synthesis and localization of inducible nitric oxide synthase mRNA (iNOS‐mRNA) and iNOS protein in the cultures of human monocytes (Mφ) and colon carcinoma cell line (DeTa) that resulted in nitric oxide (NO) synthesis has been studied. The iNOS‐mRNA was observed around the sixth hour of culture and peaked at the twelfth hour. The iNOS‐mRNA, as determined by the in situ hybridization and iNOS protein, as detected by staining with specific anti‐iNOS monoclonal antibodies, were observed preferentially in the cytoplasm of some Mφ, but not in cancer cells. Mφ cultured alone did not show detectable iNOS‐mRNA expression and iNOS protein. Mφ sorted out from tumor cells after 8hof co‐culture expressed iNOS protein and iNOS‐mRNA, which were not detected in Mφ without previous contact with cancer cells. Prevention of NO synthesis by (L‐N 5‐1‐iminoethyl)‐ornithine (L‐NIO) partly inhibited Mφ cytotoxic activity against DeTa (NO‐inducing cancer cell line) but not against the human pancreatic cancer (HPC‐4) cell line that does not induce NO production in Mφ. This suggests that Mφ cytotoxic activity, at least in some cases, may be NO dependent. These observations provide further evidence that Mφ can be directly stimulated by cancer cells for de novo production of NO and suggest that iNOS occurring in the tumor‐infiltrating macrophages may arise as a result of their interactions with tumor cells. However, because only some tumor cells are able to induce NO production in a small proportion of Mφ, its role in the anti‐tumor response of the host is probably limited. J. Leukoc. Biol. 65: 597–604; 1999.

“Activated” monocytes in gastric cancer patients

SummaryThe Fc receptor expression, antibody-dependent cellular cytotoxicity (ADCC), and nitro-blue tetrazolium (NBT) reduction of peripheral blood monocytes from 150 patients with different stages of gastric cancer was assessed and compared with results obtained in 77 normal persons and 104 patients with non-malignant diseases of the gut. Monocytes of cancer patients showed an increased ability to form rosettes with human 0, Rh+ erythrocytes coated with D-specific antibody. ADCC and NBT reduction were also elevated but no correlation was found with the stage of disease. However, all these phenomena were related to the tumor load as elevated values were the same 4–6 months after surgery in the unresectable-tumor group, while they decreased in patients with resectable tumors. These observations suggest that monocytes of some cancer patients are functionally altered (“activated”) in the course of disease.