Physical and functional association of the T cell receptor and the T3 molecular complex on cytotoxic T cell clones that are differentially inhibitable by anti-T3 antibodies

Expression of the adhesion molecule ICAM-1 and major histocompatibility complex class I antigens on human tumor cells is required for their interaction with autologous lymphocytes in vitro

In a group of 30 human tumors, comprising 12 lung, 14 ovarian, 2 breast carcinomas, 1 hypernephroma and 1 mid-gut carcinoid, the expression of major histocompatibility complex (MHC) class I molecules and the intercellular adhesion molecule 1 (CAM-1, CD54) was found to vary independently. Some tumors expressed both or neither of these molecules. Among 9/13 ICAM-1+ tumors, in which greater than 50% cells reacted with the anti-ICAM-1 monoclonal antibody (mAb) (LB-2), the class I antigen was also detected on greater than 50% of the cells. Only 2 ICAM-1+ tumors were class-I-. In 5/17 cases the tumors were MHC-class-I+ and ICAM-1-. Lymphocytes collected from the blood or from the tumor site were assayed for recognition on the tumor cells in the auto-tumor cytotoxicity test and in mixed lymphocyte tumor cell culture (MLTC). Positive results were obtained only with the MHC-class-I+/ICAM-1+ tumors. In vitro treatment of the tumor cell suspensions with interferon gamma and tumor necrosis factor alpha (TNF alpha) induced or enhanced the ICAM-1 and/or class I antigen expression in 8/12 cases. Of the tumor samples treatged, 8/9 acquired stimulatory capacity and 3/10 became susceptible to lysis by the lymphocytes. In 6/6 MLTC performed with the cytokine-treated tumor cells, cytotoxicity against the autologous tumor was generated. Three of these MLTC lymphocytes also lysed the untreated targets. mAb directed to class I antigens or to ICAM-1 inhibited both the stimulation by and the lysis of tumor cells when confronted with fresh lymphocytes. The cytotoxicity generated in the MLTC was also inhibited. If, however, the cytotoxic function was induced in MTLC containing interleukin-2 (5 U/ml), inhibition was obtained only by pretreatment of the targets with mAb against ICAM-1. The results show thus (a) that the lymphocytes react in vitro with tumor cells only if these express both MHC class I molecules and ICAM-1; (b) that expression of these molecules can be induced by interferon alpha and TNF alpha; (c) that cytotoxic effectors generated in the MLTC with cytokine-treated tumors can also act on the untreated tumor cells. The requirement of the two surface moieties for the interaction with lymphocytes was also substantiated by blockade with relevant mAb.

Auto-tumor immunity in patients with solid tumors: participation of CD3 complex and MHC class I antigens in the lytic interaction

In a number of experiments performed with blood lymphocytes of patients, the high density subset lysed autologous tumor cells separated from the surgical specimens. The lysis was abrogated by pretreatment of the effector cells with antibodies (OKT3) directed against the T3 molecule associated with the T cell receptor and by pretreatment of the target cells with antibodies (W6/32) directed against the monomorphic part of the MHC class I antigens. This subset lyses only autologous tumor cells. The selectivity and the characteristics shared with antigen specific cytotoxic T lymphocytes (CTL) suggest that the auto-tumor lysis by the effectors reflects an immune response against the tumor cells. The low density lymphocytes, separated from the blood, can lyse both auto- and allogeneic tumor cell. In the autologous system, incubation of the effectors with the mAb OKT3 had no inhibitory effect and incubation of the targets with the anti W6/32 mAb inhibited their lysis only in some experiments. The nature of the reactivity of the LD lymphocytes remains to be defined. Whether it is similar to the indiscriminative natural killing or whether part of these lymphocytes are antigen(s) specific and exhibit a high avidity interaction with the target remains to be seen. It is possible that both types of target recognition occur since the LD lymphocyte population is heterogeneous.