Murine T cells with invariant gamma delta antigen receptors: origin, repertoire, and specificity.

T cells bearing invariant gamma delta T cell antigen receptors localize to distinct epithelial sites in the adult mouse. These gamma delta T cells differ from the lymphoid alpha beta and gamma delta T cells in several ways. The epithelial gamma delta T cells appear to be the product of the earliest waves of TCR expressing cells in the fetal thymus. Additionally, the rearranged TCR junctions exhibit a distinct lack of diversity, possibly a result of the fetal origin and a specialized selection process. The use of a single invariant TCR and strict tissue localization suggest that these gamma delta T cells may provide a specialized function in the epithelial tissues distinct from that of the circulating alpha beta and gamma delta T cells.     

Regulation of antigen uptake, migration, and lifespan of dendritic cell by Toll-like receptors

Dendritic cells (DCs) sense the presence of pathogens through germline-encoded pattern recognition receptors (PRRs), which recognize molecular patterns expressed by various microorganisms and endogenous stimuli. Toll-like receptors (TLRs) are the best characterized PRRs. TLR activation has a profound effect on a number of DC activities, including endocytosis, cytoskeleton rearrangement, migration, antigen processing and presentation, survival, and death. The goal of TLR-induced DC reprogramming is to promote the appropriate activation and differentiation of lymphocytes bearing clonally distributed antigen-specific receptors. In this review, we will focus on the functional consequences of TLR engagement for conventional DCs.     

Relationship between E receptors and a T-specific surface antigen on human T cells.

The aim of this study was the delineation of different antigenic surface determinants on the surface of adult peripheral T cells by means of a specific horse anti-human T-cell serum (ATS). It was shown that this serum reacts both with E receptors and (an) additional T antigen(s). While E receptors showed the already known susceptibility to trypsin, T antigens (as demonstrated in cytotoxicity tests) were resistant to trypsinization even at high concentration. Incubation of the trypsinized peripheral blood lymphocytes (PBL) in 5 per cent CO2 allowed the resynthesis of E-receptors. High concentrations of ATS (without complement) significantly inhibited rosette-formation. This suggests a close steric relationship between E receptors and T antigen(s). However, absorptions of ATS with trypsinized PBL left the E-rosette inhibitory capacity unaltered. Treatment of PBL with ATS in appropriate dilutions and indirect immunofluorescence tests under capping conditions followed by conventional rosette procedures showed that the E receptor and T antigens are separately mobile within the T-cell membrane.     

The function of T cells carrying receptors for complexes of Ig and antigen.

Thymocytes exposed briefly in vitro to a variety of particulate substances (such as mycobacteria, erythrocytes of allogeneic cells) or to substances known to act in vivo as adjuvants (LPS or poly A:U), generate supernates which are able to induce cytophilic Ig in normal mouse serum in the presence of a foreign protein (antigen). This cytophilic Ig is taken up by 20-25% of splenic T cells. Hydrocortisone resistant thymocytes show the same property, while bone marrow cells are inactive. This activity is similar to that reported previously as being present in the 4S fraction of mouse serum, collected 6 hours after injection of complete Freund's adjuvant. It is proposed that this factor is responsible for the formation of complexes of Ig and antigen which have been detected in the serum 6 hours after immunization. Thymocytes collected 6 hours after priming in vivo with SRBC (when a subpopulation among them carries easily demonstrable surface Ig) are able to amplify markedly the antibody response particularly the 7S. It is postulated that the factor by generating the cytophilic Ig (complexes?) which is taken up by T cells, sets up a mechanism which markedly amplifies their helper cell function.     

Elevated numbers of peripheral T cells in inflammatory bowel diseases displaying T9 antigen and Fc alpha receptors.

Elevated numbers of peripheral T cells expressing the activation associated antigen T9 are found in patients with active Crohn's disease. Expression of T9 is found to be correlated to the activity of the disease. However the presence of activated peripheral T cells is not restricted to Crohn's disease, but could also be found in other maladies with a supposed involvement of the immune system, e.g. ulcerative colitis, sarcoidosis, connective tissue disease and after organ transplantation. Significant elevation of the number of activated T cells could not be detected in cases of viral or bacterial enteritis and coeliac disease. Analysing the subset of T9 positive T cells with regard to the expression of Fc alpha receptors, a significantly increased number of Fc alpha receptor positive cells, within the subset of T9 positive cells in the peripheral blood of patients with Crohn's disease and ulcerative colitis was found, which could not be demonstrated in the case of other diseases analysed in this study. Thus the T9+ Fc alpha receptor +T cell subset may be considered to be pathognomonic for inflammatory bowel diseases. Analysis of the regulatory properties of T9 positive cells, with regard to the immunoglobulin isotype secretion in a pokeweed mitogen stimulated autologeous B cell assay, suggests that peripheral T9 positive T cells are involved in the suppression of IgA synthesis or secretion.     

Human T cell clones allospecific for HLA-DR5 antigen with the OKT8 phenotype

Human allospecific T-lymphocyte clones reactive in the primed lymphocyte (PLT) and/or the CML assays were established and grown using T cell growth factor and weekly stimulation with a pool of allogeneic feeder cells. Specificity of selected clones was determined by their reactivity with a panel of HLA-typed lymphocytes. The phenotype of the clones was identified by monoclonal antibodies and complement lysis. Two weakly cytolytic clones, which specifically proliferated in response to DR5 bearing lymphocytes in PLT, possessed the OKT8 marker, suggesting that this determinant is not exclusively involved in the recognition of class I antigens.     

T lymphocytes in giant cell arteritic lesions are polyclonal cells expressing alpha beta type antigen receptors and VLA-1 integrin receptors.

Giant cell arteritis (GCA) is a common disease in the elderly. It is characterized by focal inflammatory lesions dominated by T lymphocytes and macrophages. The etiology of GCA is, however, still unknown. The aim of the present study was to determine whether lesional T cells represent clonal proliferations, and to characterize adhesion receptors that could be important for recruitment of T cells and antigen receptors involved in their activation. Temporal artery biopsies were obtained from 13 patients presenting with clinical signs of GCA. Immunohistochemistry was used to characterize cell surface receptors on CD3+ T cells in situ in the lesions of eight patients with biopsy-verified GCA. The overwhelming majority of T cells in GCA lesions expressed the TCR alpha beta receptors. In sections from three of eight patients, a small proportion of cells expressing TCR gamma delta was also seen. Almost all T cells expressed the integrin receptors, LFA-1 and VLA-1, as determined by double-staining. To characterize the clonal composition of the lesional T cell population, cells were isolated by collagenase digestion of two lesions and T cells cloned by limiting dilution in the presence of mitogenic antibodies, IL-2 and autologous feeder cells. Rearrangements of the T cell receptor (TCR) genes of the clones were analysed by Southern hybridization using probes for TCR gamma and beta genes. T cell clones established from GCA lesions exhibited heterogeneous rearrangement patterns, indicating a polyclonal origin of the cells. We conclude that GCA lesions contain T lymphocytes that are of polyclonal origin and express integrin-type adhesion receptors. This supports the hypothesis that GCA involves an inflammatory response during which polyclonal T cells adhere to arterial tissue components and accumulate in the developing lesions.     

T cells expressing CD26-specific chimeric antigen receptors exhibit extensive self-antigen-driven fratricide

Abstract

Background: Immunotherapy utilizing T cells genetically modified to express chimeric antigen receptors (CARs) is rapidly emerging as a promising novel treatment for hematological and nonhematological malignancies. In order to target the TKI-insensitive leukemia stem cells (LSCs) in chronic myeloid leukemia (CML) by CAR T cells, we chose CD26 as a cell surface tumor-associated antigen due to preferentially expression on LSCs. Additionally, CD26 has also been suggested to be a multipurpose therapeutic target for other cancer. Therefore, developing the CD26-targeting CAR T cells may be a promising therapy for not only LSCs but also other CD26+ cancer cells.

Methods: We designed the second-generation CD26-targeting CAR utilizing 4-1BB (CD137) as costimulatory domain, and transduced T cells with CD26-CAR containing lentiviral. Then we evaluated the transduction efficiency and expansion ability, and demonstrated the existence of self-antigen-driven fratricide by cytokine assay and cytotoxicity assay.

Results: Anti-CD26-4-1BB-CAR T cells exhibited poor viability, multiple cytokine secretion, down-regulation of CD26 and direct cytotoxicity against themselves, indicating self-antigen-driven fratricide.

Conclusion: Eradicating CML-LSCs via anti-CD26-4-1BB-CAR T cells is not applicable, and optimized design or alternative target is needed.     

How T cells 'see' antigen

T lymphocytes bearing alphabeta T cell receptors are pivotal in the immune response of most vertebrates. For example, helper T cells orchestrate antibody production by B cells as well as stimulating other cells, whereas cytotoxic T cells kill virally infected or abnormal cells. Regulatory T cells act to dampen responsiveness, and natural killer-like T cells monitor lipid metabolism. The specificity of these cells is governed by the alphabeta T cell receptors - antibody-like heterodimeric receptors that detect antigenic fragments (peptides) or lipids bound to histocompatibility molecules. Intriguing clues as to how these peculiar ligands are recognized have gradually emerged over the years and tell a remarkable story of biochemical and cellular novelty. Here we summarize some of the more recent work on alphabeta T cell receptor recognition and discuss the implications for activation.     

Myelin antigen reactive T cells in cerebrovascular diseases.

T cell reactivities to the putative autoantigens myelin basic protein (MBP), MBP peptides with amino acid residues 110-128 and 148-165, and myelin proteolipid protein (PLP) were examined in patients with acute ischaemic cerebrovascular disease (CVD) and, for comparison, in patients with inflammatory neurological diseases and other neurological diseases. A quantitative measure of these T cell reactivities was obtained by assessing numbers of T cells among blood and cerebrospinal fluid (CSF) mononuclear cells that secreted IFN-gamma in response to antigen in vitro. Higher numbers of T cells reactive with each of these four antigens were detected in peripheral blood from patients with CVD compared with patients of the two control groups. Among blood cells from the CVD patients, their average number was 2.3-4.2/10(5) mononuclear cells. MBP reactive T cells were several-fold enriched in the CSF of CVD patients. The findings strongly suggest that brain damage in context with acute CVD leads to an in vivo expansion of myelin reactive T cells.     

Defective induction of antigen-reactive proliferating T cells in B cell-deprived mice. II. Anti-mu treatment affects the initiation and recruitment of T cells

Mice injected from day of birth onwards with rabbit anti-mouse IgM (antim-mu) antibodies were found to be B cell-deficient and defective for the induction of antigen-reactive proliferating T cells (TPRLF). This defective induction was not due to the absence of circulating antigen-specific antibodies since the daily injections of such antibodies during exposure to antigen did not restore the ability of anti-IgM treated animals to generate TPRLF. Analyzing the cellular events implicated in the induction of virgin antigen-reactive T cells, anti-mu-treated mice manifested impairment of the three interacting cell types involved in the induction of TPRLF. Thus, peritoneal and splenic antigen-presenting cells from such animals were impaired in their capacity to signal a primary antigen-specific T cell reaction. Their splenic lymphocytes could not function as initiator cells in transferring immunogenic signals to recruit TPRLF in normal recipients. Potent antigen-specific splenic initiator cells failed to induce the recruitment of specific TPRLF in anti-mu-treated mice. The defective induction of TPRLF in anti-mu-treated mice may be due to a functional impairment of cells expressing membrane-bound IgM molecules which seemingly play a central role in the transfer of immunogenic signals for the recruitment of antigen-specific circulating T cells. We suggest that splenic B cells function as initiators in the transfer of antigen-induced signals from peritoneal antigen-presenting cells to T cells. These seems to be the primary targets of anti-mu treatment.     

Subpopulations of mouse T lymphocytes. II. Suppression of graft-vs.-host reactions by naturally proliferating splenic T cells.

The immunological role of a naturally proliferating subpopulation of splenic T cells was investigated using the graft-vs.-host (GvH) reaction on the mouse. Normal parental spleen cells, purified splenic T cells or lymph node cells were pulse-treated for one hour in vitro with tritiated thymidine of high specific activity ([3H]dThd, "thymidine suicide"). The treatment specifically and selectively kills proliferating cells which are actively synthesizing DNA, i.e. cells in S phase. Following treatment, the cells were transferred to F1 recipients and the GvH reaction measured by the splenomegaly assay. The results showed that the GvH effector cells in the donor spleen and lymph node are nonproliferating T cells. Furthermore, donor spleen cells treated with [3H]dThd consistently had enhanced GvH reactivity when compared to the controls, while the phytohemagglutinin response of these same treated cell suspensions was significantly inhibited. When purified splenic T cells were used, treatment with [3H]dThd also caused an increase in the GvH reaction, showing that a T cell population was being affected by the cycleactive agent. These results indicated that some naturally proliferating T cells have suppressor functions, and their specific inactivation allows nonproliferating effector T cells to mount a more vigourous GvH reaction.     

Evidence of limited variability of antigen receptors on intrathyroidal T cells in autoimmune thyroid disease

BACKGROUND. Patients with autoimmune thyroid diseases, including Graves' disease and Hashimoto's disease, have marked lymphocytic infiltration in their thyroid glands. We examined the gene for the variable regions of the alpha-chain of the human T-cell receptor (the V alpha gene) in intrathyroidal T cells to determine whether the infiltration is a secondary heterogeneous immune response or a more restricted, and therefore primary and presumably pathogenetic, reaction to thyroid autoantigens. METHODS. We used the polymerase chain reaction to detect small numbers of T cells expressing the variable region of the V alpha gene. Different oligonucleotides were used to amplify complementary DNA for the 18 known families of the V alpha gene in intrathyroidal T cells from 9 patients with autoimmune thyroid disease. We compared the findings with the results in patients with nonautoimmune thyroid disease as well as those in normal subjects. RESULTS. We found marked restriction in the expression of T-cell-receptor V alpha genes by T cells from the thyroid tissue of patients with autoimmune thyroid disease. An average of only 5 of the 18 V alpha genes were expressed in such samples, as compared with 17 V alpha genes expressed in peripheral-blood T cells from the same patients. No such restriction was found in thyroid tissue from patients with nonautoimmune thyroid disease. The predominantly expressed V alpha genes differed from patient to patient, however, with no clear association with the type of disease. CONCLUSIONS. Intrathyroidal T-cell accumulation in autoimmune thyroid disease is highly restricted and points to the primacy of T cells in causing thyroid disorders. These results present the possibility of using antibodies to the T-cell receptor for the specific inhibition of abnormal T-cell function in autoimmune thyroid disease.     

The delineation of antigen receptors on human T lymphocytes

Monoclonal antibodies have identified several surface molecules involved in target cell recognition by cytotoxic human T cells. In this article it is proposed that T cells have two recognition units: a complex composed of the T3 molecule and a clonally unique glycoprotein which binds antigen associated with polymorphic MHC gene product; and the T4 or T8 molecule which binds to a constant region of an MHC gene product.     

The relationship between MHC restricted and allospecific T cell recognition

The existence in the mature T cell repertoire of a high precursor frequency of cells which recognise allogeneic MHC molecules appears to contradict the well-established dogma of positive selection for self MHC restriction. In order to explore the possibility that alloreactive cells are derived from a fraction of the repertoire that is not self-MHC-restricted, the contribution of in vivo-primed T cells to "primary" alloresponses was investigated. Peripheral blood T cells were separated into virgin and memory populations by sorting for low and high levels of LFA-3 expression, and their proliferative responses to MHC incompatible stimulator cells was quantitated. The results demonstrated that approximately half of a "primary" alloresponse is contributed by previously primed T cells that, by definition, must be self-MHC restricted. Furthermore it was possible to define the original MHC-restricted antigen specificity of two T cell clones raised against the allospecific HLA-DR1 from a DR4Dw4/DRw13DW19 responder. The emerging consensus view that anti-MHC alloreactive T cells, like antigen-specific T cells, are specific for MHC/peptide complexes, and have a parental self-MHC restriction, begs a structural explanation. Comparison of multiple DR beta 1 domain sequences reveals that DR molecules fall into groups that have extensive homology in the residues on the beta 1 domain alpha-helix that are predicted to point up towards the T cell receptor (histotopic), and thus to determine MHC restriction. Given that the DR alpha chain is invariant this creates the possibility that anti-DR allorecognition can mimic self-restricted recognition. Within these groups of histotopically similar DR products there are multiple differences in the peptide-binding residues that lie on the inner aspects of the alpha-helix or on the floor of the antigen-binding groove. As a consequence, it is predicted that a different array of endogenous peptides will be bound, due to determinant selection. Thus, allorecognition within these groups may result from the recognition of endogenous peptides that are bound by stimulator but not by responder MHC products, seen in a self-restricted manner. In combinations where histotopic similarity does not exist, allorecognition may be best explained by the chance occurrence of a receptor selected for intermediate affinity for thymically expressed MHC molecules having a higher affinity for an allogeneic histotope. Such a receptor would have been deleted in a thymus expressing the allospecificity, but would be perceived as "safe" in the absence of this MHC product.     

Transforming growth factor-beta 1 enhances the generation of allospecific cytotoxic T lymphocytes.

We investigated the effects of transforming growth factor-beta 1 (TGF-beta 1) on the proliferation and generation of murine T lymphocytes in vitro. TGF-beta 1 suppressed T- and B-lymphocyte proliferation, mixed lymphocyte reaction (MLR), and the generation of natural killer (NK) cells and lymphokine-activated killer (LAK) cells. On the other hand, TGF-beta 1 significantly enhanced the generation of allospecific cytotoxic T lymphocytes (CTL) at low concentrations (0.01-1 ng/ml) in a dose-dependent manner and restored it to the control level at higher concentrations (10-40 ng/ml). Allospecific CTL generation by TGF-beta 1 was maximally enhanced when added at the beginning of culture. Less enhancement occurred when the addition was delayed. Anti-TGF-beta 1 antibody completely abolished the enhancing effects of TGF-beta 1. Furthermore, platelet-derived TGF-beta (pTGF-beta) as well as recombinant TGF-beta 1 similarly enhanced the generation of allospecific CTL. These data demonstrate that TGF-beta has not only immunosuppressive effects but also immuno-enhancing effects in vitro.     

Defective induction of antigen-reactive proliferating T cells in B cell-deprived mice

Mice were injected from day of birth onward with rabbit anti-mouse IgM antiserum or purified rabbit anti-mouse IgM antibodies. These mice completely lacked Ig-positive cells or serum Ig, as analyzed by specific fluoresceinated antibodies on the fluorescence-activated cell sorter (FACS-II), by polyclonal B cell mitogens and by specific precipitation in agar. These animals were then primed in vivo by antigen emulsified in complete Freund's adjuvant, and, subsequently, their draining lymph nodes were tested for their T cell proliferative responses in vitro, to the relevant antigen and were found to be severely impaired. However, the antigen-presenting capacity of both spleen cells and thioglycollate-induced peritoneal cells was found to be intact.     

Granuloma cells in chronic inflammation express CD205 (DEC205) antigen and harbor proliferating T lymphocytes: Similarity to antigen‐presenting cells

Granulomas are classified as immune or foreign body granulomas. Of these, the immune granulomas, a hallmark of granulomatous inflammation, are closely related to cell‐mediated immune responses. The aim of the present study is to characterize immune granuloma cells in 33 patients with granulomatous inflammation focusing on the expression of CD205 (DEC205), a cell surface marker of antigen presenting cells, and their spatial relationship to T cells. CD205 was frequently expressed by immune granuloma cells, in contrast to foreign body granuloma cells that lacked CD205 expression. T cells were not only distributed in a lymphocyte collar around the granuloma, but also present among the granuloma cells (termed ‘intra‐granuloma T cells’). Intra‐granuloma T cells stained positive for Ki‐67 (median positivity = 9.4%) by double immunostaining for CD3 and Ki‐67. This indicated the presence of proliferative stimuli within the granuloma that could activate the intra‐granuloma T cells. The labeling index of Ki‐67 in intra‐granuloma T cells was significantly higher than that of T cells in the lymphocyte collar (P < 0.0001) or T cells in the T cell zone (paracortex) of chronic tonsillitis or reactive lymphadenitis (P = 0.002). These data indicate a close similarity between immune granulomas and antigen presenting cells.