Cellular Mechanism of Immuno-Suppression in Cancer Patients

In order to study the cellular mechanism of immunosuppression in patients with gastric and colon cancer, peripheral blood mononuclear cells from patients were fractionated to Mφ depleted, Tycell depleted and Tγ cell rich fractions and were treated with monoclonal anti-la, anti-HLB-1, 2 and anti-Leu-1, 2a, 3a antibodies. The immune response was evaluated with PHA, ConA and PWM lymphocytoblastogenesis, 3M KCI MLTI and PWM-inducing IgG synthesis. The results obtained were as follows: 1) Activated M^ played a part in non-specific immunosuppression. 2) This immunosuppression was due to the humoral factor of Mφ. 3) It was supposed that this humoral factor consisted of PG and H2O2. B cells had no immunosuppressive effect. 5) Tγ cells did not play an important role as suppressor T cells. 6) Leu-2a+ cells were worthy of notice as suppressor T cells.These cells made up the immunosuppressive-network and related escape mechanism of these tumors