MHC nonrestricted cytotoxic T cell clones with selective specificity from patients with transitional cell carcinoma (TCC) of the urinary bladder

Antigen-specific, MHC-unrestricted T cells

The published record suggests that in the majority of cases the antigen is recognized by the T cell receptor (TCR) as a complex of a foreign antigen and amino acid residues contributed by the major histocompatibility complex (MHC) antigens, and the antigen-specific, MHC-restricted effector function is an unambiguous result of this process. Alternatively, the T cell receptor may recognize a particular conformational form of the antigen which is dictated by the allelic differences in the MHC, resulting also in MHC-restricted recognition. When, however, a T cell which phenotypically fulfills all the requirements necessary to perform antigen specific, MHC-restricted function, shows a lack of MHC restriction, there are two possible explanations: 1) In addition to the MHC-restricted, antigen-specific T cell receptor the cell expresses, or has newly acquired the expression of another, MHC-unrestricted (NK-like) receptor, or 2) The specific antigen recognized by the T cell receptor, is able to bind to the receptor and activate the T cell without being presented by the MHC molecule. While the first possibility has been extensively described in the literature as well as other articles in this issue, the second possibility has not been dealt with to the same extent and is the primary focus of this review.

Ultrastructure of IL2-stimulated tumor-infiltrating lymphocytes showing cytolytic activity against tumor cells

Tumor-infiltrating lymphocytes (TIL) obtained from tumor tissue and pleural effusion of breast carcinoma were cultured with interleukin-2 (IL2) and thus activated. The ultrastructure of TIL stimulated by IL2 to kill various breast carcinoma cells was then investigated. Freshly isolated TIL cultured with autologous tumor cells for 48 h without IL2 were small, round and showed neither binding to nor killing of tumor cells. TIL stimulated to proliferate by IL2 became effector cells and showed cytotoxicity against tumor cells. Ultrastructurally, the effector TIL resembled large granular lymphocytes, and adhered to tumor cells through interdigitation or close apposition of the two plasma membranes accompanied by spot-like close membrane contacts. At the site of each spot-like contact, there was a 5-nm intercellular space. The morphology of the TIL processes did not differ from those of LAK and other CTL or NK cell processes during contact, invagination or the killing of target cells. The granules in TIL were considered to participate in the cytotoxic effect. Phenotypically heterogeneous TIL, CD8+/CD57- and CD8+/CD57+, adhered to autologous tumor cells and MCF7 (human breast carcinoma cell line). However, it was unclear which cell or cells acted as the effector for tumor-cell killing.

Cytotoxic and noncytotoxic mechanisms involved in the in vitro anti-leukaemia effects of T cell clones established from a chronic myelogenous leukaemia patient during treatment in vivo with interferon alpha

T cell clones derived from a chronic myelogenous leukaemia (CML) patient during interferon alpha (IFN alpha, Wellferon) biotherapy preferentially lysed autologous rather than allogeneic CML target cells in an apparently MHC-unrestricted fashion, but also lysed bone marrow cells from certain normal donors regardless of whether or not they shared HLA antigens with the patient. Although T cell clones inhibited both CML and normal bone marrow in the colony-forming assay, they blocked proliferation of CML cells more efficiently than bone marrow cells. This inhibitory effect was mediated at least in part by the tumour necrosis factor alpha (TNF alpha) and IFN gamma secreted by the clones. Antisera to these cytokines partially prevented inhibition. Involvement of additional factors is also suggested in blocking CML cell proliferation because this was not 100% inhibited even by a combination of TNF alpha and IFN gamma. In addition, most clones failed strongly to block the proliferation of normal bone marrow cells, which were susceptible to inhibition by these cytokines.

Persistent superphosphorylation of leukosialin (CD43) in activated T cells and in tumour cell lines

CD43 (leukosialin) is a highly sialylated, single-chain molecule expressed on most human leucocytes. Regulatory signals appear to be transduced through the molecule as suggested by the ability of anti-CD43 antibodies to induce aggregation and proliferation of T cells and to enhance B-cell proliferation and natural killer cell activity. Activation of protein kinases is an essential event in signal transduction. We were therefore interested to study whether CD43 may function as a substrate for protein kinases during mitogenic activation of lymphocytes. We show that CD43 was rapidly superphosphorylated (within minutes) on serine residues following addition of phorbol ester (PMA) to peripheral blood lymphocytes. PMA treatment of the cells was not followed by rapid down-regulation of CD43. Activation of the lymphocytes by concanavalin A or anti-CD3 antibodies (OKT-3) also resulted in superphosphorylation of CD43. However, the phosphorylation was delayed as compared to that induced by PMA and was detected 3-4 h after the addition of the reagents. A plateau was reached after 24-48 h of stimulation. Interestingly, the high level of phosphorylation of CD43 was maintained in long-term cultures of T cells activated by various means. Furthermore, CD43 was found to be constitutively superphosphorylated (on serine and tyrosine) in continuously growing cell lines of T, B, and non-lymphoid origin. Taken together, the results suggest that CD43 has an important role during both early and late phases of T-cell activation and that modulation of its biochemical properties by protein kinases may be associated with progression through the cell cycle and with cellular growth.