Coronary arteries from human cardiac allografts with chronic rejection contain oligoclonal T cells: persistence of identical clonally expanded TCR transcripts from the early post-transplantation period (endomyocardial biopsies) to chronic rejection (coronary arteries)

Human abdominal aortic aneurysm (AAA): Evidence for an autoimmune antigen-driven disease

Abdominal aortic aneurism (AAA) is a complex immunological disease with a strong genetic component, and one of the ten leading causes of death of individuals 55-74 years old worldwide. Strong evidence has been accumulated suggesting that AAA is an autoimmune specific antigen-driven disease. Mononuclear cells infiltrating AAA lesions comprised of T and B lymphocytes and other cells expressing early-, intermediate- and late-activation antigens, and the presence of antigen-presenting cells have been documented, demonstrating an ongoing immune response. The three components of the trimolecular complex, T-cell receptor (TCR)/peptide (antigen)/HLA have been identified in AAA, and specifically: (i) clonal expansions of T-cell clones in AAA lesions; (ii) the association of AAA with particular HLA Class I and Class II; and (iii) self or nonself putative AAA-associated antigens. IgG autoantibodies recognizing proteins present in normal aortic tissue have been reported in patients with AAA. Molecular mimicry, defined as the sharing of antigenic epitopes between microorganisms (bacteria, viruses) and self antigens, maybe is responsible for T-cell responses and antibody production in AAA. Also, the frequency and the suppressor activity of CD4 + CD25 + FOXP3+ Tregs and the expression of FOXP3 transcripts and protein have been reported to be significantly impaired in AAA patients vs normal donors.

Specific Follicular Helper T Cell Signature in Takayasu Arteritis

OBJECTIVE

Our aim was to compare transcriptome and phenotype profiles of CD4+ T cells and CD19+ B cells in patients with Takayasu arteritis (TAK), patients with giant cell arteritis (GCA), and healthy donors.

METHODS

Gene expression analyses, flow cytometry immunophenotyping, T cell receptor (TCR) gene sequencing, and functional assessments of cells from peripheral blood and arterial lesions from TAK patients, GCA patients, and healthy donors were performed.

RESULTS

Among the most significantly dysregulated genes in CD4+ T cells of TAK patients compared to GCA patients (n = 720 genes) and in CD4+ T cells of TAK patients compared to healthy donors (n = 1,447 genes), we identified a follicular helper T (Tfh) cell signature, which included CXCR5, CCR6, and CCL20 genes, that was transcriptionally up-regulated in TAK patients. Phenotypically, there was an increase in CD4+CXCR5+CCR6+CXCR3- Tfh17 cells in TAK patients that was associated with a significant enrichment of CD19+ B cell activation. Functionally, Tfh cells helped B cells to proliferate, differentiate into memory cells, and secrete IgG antibodies. Maturation of B cells was inhibited by JAK inhibitors. Locally, in areas of arterial inflammation, we found a higher proportion of tertiary lymphoid structures comprised CD4+, CXCR5+, programmed death 1+, and CD20+ cells in TAK patients compared to GCA patients. CD4+CXCR5+ T cells in the aortas of TAK patients had an oligoclonal α/β TCR repertoire.

CONCLUSION

We established the presence of a specific Tfh cell signature in both circulating and aorta-infiltrating CD4+ T cells from TAK patients. The cooperation of Tfh cells and B cells might be critical in the occurrence of vascular inflammation in patients with TAK.

Clonally expanded alpha-chain T-cell receptor (TCR) transcripts are present in aneurysmal lesions of patients with Abdominal Aortic Aneurysm (AAA)

Abdominal aortic aneurysm (AAA) is a life-threatening immunological disease responsible for 1 to 2% of all deaths in 65 year old or older individuals. Although mononuclear cell infiltrates have been demonstrated in AAA lesions and autoimmunity may be responsible for the initiation and account for the propagation of the disease, the information available about the pathogenesis of AAA is limited. To examine whether AAA lesions from patients with AAA contain clonally expanded α-chain TCR transcripts, we amplified by the non-palindromic adaptor-PCR (NPA-PCR)/Vα-specific PCR and/or the Vα-specific PCR these α-chain TCR transcripts. The amplified transcripts were cloned and sequenced. Substantial proportions of identical α-chain TCR transcripts were identified in AAA lesions of 4 of 5 patients, demonstrating that clonally expanded T cells are present in these AAA lesions. These results were statistically significant by the bimodal distribution. Three of 5 of these patients were typed by DNA-based HLA-typing and all three expressed DRB1 alleles containing the DRβGln70 amino acid residue that has been demonstrated to be associated with AAA. All three patients exhibited clonally expanded T cells in AAA lesions. Four of the 5 patients with AAA who exhibited clonal expansions of α-chain TCR transcripts, also exhibited clonal expansions of β-chain TCR transcripts in AAA lesions, as we have demonstrated previously (J Immunol 192:4897, 2014). αβ TCR-expressing T cells infiltrating AAA lesions contain T-cell clones which have undergone proliferation and clonal expansion in vivo in response to as yet unidentified specific antigens that may be self or nonself. These results provide additional evidence supporting the hypothesis that AAA is a specific antigen-driven T-cell autoimmune disease.

T Cell Receptor Profiling in Type 1 Diabetes

PURPOSE OF REVIEW

The genetic susceptibility and dominant protection for type 1 diabetes (T1D) associated with human leukocyte antigen (HLA) haplotypes, along with minor risk variants, have long been thought to shape the T cell receptor (TCR) repertoire and eventual phenotype of autoreactive T cells that mediate β-cell destruction. While autoantibodies provide robust markers of disease progression, early studies tracking autoreactive T cells largely failed to achieve clinical utility.

RECENT FINDINGS

Advances in acquisition of pancreata and islets from T1D organ donors have facilitated studies of T cells isolated from the target tissues. Immunosequencing of TCR α/β-chain complementarity determining regions, along with transcriptional profiling, offers the potential to transform biomarker discovery. Herein, we review recent studies characterizing the autoreactive TCR signature in T1D, emerging technologies, and the challenges and opportunities associated with tracking TCR molecular profiles during the natural history of T1D.

Aneurysmal lesions of patients with abdominal aortic aneurysm contain clonally expanded T cells

Abdominal aortic aneurysm (AAA) is a common disease with often life-threatening consequences. This vascular disorder is responsible for 1-2% of all deaths in men aged 65 years or older. Autoimmunity may be responsible for the pathogenesis of AAA. Although it is well documented that infiltrating T cells are essentially always present in AAA lesions, little is known about their role in the initiation and/or progression of the disease. To determine whether T cells infiltrating AAA lesions contain clonally expanded populations of T cells, we amplified β-chain TCR transcripts by the nonpalindromic adaptor-PCR/Vβ-specific PCR and/or Vβ-specific PCR, followed by cloning and sequencing. We report in this article that aortic abdominal aneurysmal lesions from 8 of 10 patients with AAA contained oligoclonal populations of T cells. Multiple identical copies of β-chain TCR transcripts were identified in these patients. These clonal expansions are statistically significant. These results demonstrate that αβ TCR(+) T lymphocytes infiltrating aneurysmal lesions of patients with AAA have undergone proliferation and clonal expansion in vivo at the site of the aneurysmal lesion, in response to unidentified self- or nonself Ags. This evidence supports the hypothesis that AAA is a specific Ag-driven T cell disease.

Advances in direct T-cell alloreactivity: function, avidity, biophysics and structure

Although T-cell-based adaptive immunity plays a crucial role in protection against infectious pathogens and uncontrolled outgrowth of malignant cells, a large portion of these T cells are also capable of responding to allogeneic HLA molecules, violating the paradigm of self-major histocompatibility complex (MHC) restriction. Recent studies have provided insights into the mechanisms by which these T cells recognize allogeneic targets. The role of antiviral T cells in direct alloreactivity through peptide-dependent molecular mimicry and alternate peptide-MHC docking modes has emerged as major models for the human alloresponse. Here, we review in depth recent advances in this field and discuss how molecular interactions between T cells and HLA molecules drive the activation of these effector cells and its potential implications for alloreactivity in human transplantation.

Human breast tumor cells express IL-10 and IL-12p40 transcripts and proteins, but do not produce IL-12p70

IL-10 transcripts were expressed in 14/15 primary breast adenocarcinomas and in 5/8 established breast tumor lines. Immunohistochemistry and immunoprecipitation from lysates and supernatants revealed that established breast tumor lines produced IL-10 protein. Immunohistochemistry revealed that IL-10 is localized to tumor cells of primary breast adenocarcinomas and to occasional infiltrating MNC. Established breast tumor cell lines expressed IL-12p40 transcripts (6/8) and protein (4/7) and IL-12p35 transcripts (6/7). Using two sandwich ELISAs, specific, respectively, for IL-12p40 and IL-12p70 proteins, we demonstrated that established breast tumor cell lines produce IL-12p40 monomer/homodimer, but not IL-12p70. Positive staining for IL-12p70 in primary breast adenocarcinomas was found only in MNC infiltrating the tumor while tumor cells were negative. IL-12p40 homodimer/monomer inhibit as antagonists IL-12 or IL-23, although they may also act as agonists and positive regulators. Also, primary breast adenocarcinomas (15/15) and established breast tumor cell lines (6/8) expressed TGF-β1 transcripts. IL-10, IL-12p40 and TGF-β1 may inhibit substantially the anti-tumor immune response.

Generation of NO by bystander human CD8 T cells augments allogeneic responses by inhibiting cytokine deprivation-induced cell death

Nitric oxide (NO), generated by inducible NO synthase (iNOS) in bystander human CD8 T cells, augments the accumulation of allogeneically activated human CD8 T cells in vitro and in vivo. Here, we report that iNOS-derived NO does not affect T-cell proliferation but rather inhibits cell death of activated human CD8 T cells after activation by allogeneic endothelial cells in culture. Exogenous NO did not affect activation-induced cell death of human CD8 T cells but specifically reduced death of activated T cells due to cytokine deprivation. NO-mediated inhibition of T-cell death did not involve cGMP signaling, and NO did not affect the expression of Bcl-2-related proteins known to regulate cytokine deprivation-induced cell death. However, NO inhibited the activity of caspases activated as a consequence of cytokine deprivation in activated T cells. This protective effect correlated with S-nitrosylation of caspases and was phenocopied by z-VAD.fmk and z-LEHD.fmk, pharmacological inhibitors of caspases. In summary, our findings indicate that NO augments the accumulation of activated human T cells principally by inhibiting cytokine deprivation-induced cell death through S-nitrosylation of caspases.

The lymphocytic infiltration in calcific aortic stenosis predominantly consists of clonally expanded T cells

Valve lesions in degenerative calcific aortic stenosis (CAS), a disorder affecting 3% of those older than 75 years, are infiltrated by T lymphocytes. We sought to determine whether the alphabeta TCR repertoire of these valve-infiltrating lymphocytes exhibited features either of a polyclonal nonselective response to inflammation or contained expanded clones suggesting a more specific immune process. TCR beta-chain CDR3-length distribution analysis using PCR primers specific for 23 Vbeta families performed in eight individuals with CAS affecting tri- or bileaflet aortic valves revealed considerable oligoclonal T cell expansion. In five cases, beta-chain nucleotide sequencing in five selected Vbeta families showed that an average of 92% of the valve-infiltrating T cell repertoire consisted of expanded T cell clones, differing markedly in composition from the relatively more polyclonal peripheral CD8 or CD4 T cell subsets found even in this elderly population. Twenty-four of the valve-infiltrating T cell clones also had the same clone identified in blood, some of which were highly expanded. Interestingly, 22 of these 24 shared clones were CD8 in lineage (p = 1.5 x 10(-12)), suggesting a possible relationship to the expanded CD8(+)CD28(-) T cell clones frequently present in the elderly. Additionally, the sequences of several TCR beta-chain CDR3 regions were homologous to TCR beta-chains identified previously in allograft arteriosclerosis. We infer that these findings are inconsistent with a nonselective secondary response of T cells to inflammation and instead suggest that clonally expanded alphabeta T cells are implicated in mediating a component of the valvular injury responsible for CAS.

Interferon-γ Axis in Graft Arteriosclerosis

Cardiac transplantation is the most effective treatment for advanced heart failure. Despite improvements in immunosuppression therapy that prevent acute rejection, cardiac allografts fail at rates of 3% to 5% per posttransplant year. The hallmark morphological lesion of chronically failing cardiac allografts, also seen in chronic renal and liver graft failure, is luminal stenosis of blood vessels, especially of conduit arteries. Late graft failure results from widespread secondary ischemic injury to the graft parenchyma rather than direct immune-mediated damage. Although this process affects the entire graft vasculature, graft arteriosclerosis is a suitable term to describe the problem because it applies to different types of failing organs and because it emphasizes the central feature, namely an accelerated form of arterial injury and remodeling. The precise pathogenesis of graft arteriosclerosis is unknown. In this review, we make the case that the signature T-helper type 1 cytokine, interferon (IFN)-γ, is a key effector in graft arteriosclerosis, which, together with the IFN-γ–inducing cytokine interleukin-12 and IFN-γ–inducible chemokines such as CXCR3 ligands, constitute a positive feedback loop for T-cell activation, differentiation, and recruitment that we refer to as the IFN-γ axis. We evaluate the evidence to support this hypothesis in clinical observational and experimental animal studies. Additionally, we examine the regulation of IFN-γ production within the artery wall, the effects of IFN-γ on vessel wall cells, and the outcome of therapeutic agents on IFN-γ production and signaling. These observations lead us to suggest that new therapies for graft arteriosclerosis should be optimized which focus on reducing IFN-γ synthesis or actions.

Abdominal aortic aneurysm is a specific antigen-driven T cell disease

To determine whether monoclonal/oligoclonal T cells are present in abdominal aortic aneurysm (AAA) lesions, we amplified beta-chain T cell receptor (TCR) transcripts from these lesions by the nonpalindromic adaptor (NPA)-polymerase chain reaction (PCR)/V-beta-specific PCR followed by cloning and sequencing. Sequence analysis revealed the presence of substantial proportions of identical beta-chain TCR transcripts in AAA lesions in 9 of 10 patients examined, strongly suggesting the presence of oligoclonal populations of alphabeta TCR+ T cells. We have also shown the presence of oligoclonal populations of gammadelta TCR+ T cells in AAA lesions. Sequence analysis after appropriate PCR amplification and cloning revealed the presence of substantial proportions of identical VgammaI and VgammaII TCR transcripts in 15 of 15 patients examined, and of Vdelta1 and Vdelta2 TCR transcripts in 12 of 12 patients. These clonal expansions were very strong. All these clonal expansions were statistically significant by the binomial distribution. In other studies, we determined that mononuclear cells infiltrating AAA lesions express early- (CD69), intermediate- (CD25, CD38), and late- (CD45RO, HLA class II) activation antigens. These findings suggest that active ongoing inflammation is present in the aortic wall of patients with AAA. These results demonstrate that oligoclonal alphabeta TCR+ and gammadelta TCR+T cells are present in AAA lesions. These oligoclonal T cells have been clonally expanded in vivo in response to yet unidentified antigens. Although the antigenic specificity of these T cells remains to be determined, these T cells may play a significant role in the initiation and/or the propagation of the AAA. It appears that AAA is a specific antigen-driven T cell disease.

The non-palindromic adaptor-PCR method for the identification of the T-cell receptor genes of an interferon-gamma-secreting T-cell hybridomaspecific for trans-sialidase, an immunodominant Trypanosoma cruzi antigen

Cloning of the T-cell receptor genes is a critical step when generating T-cell receptor transgenic mice. Because T-cell receptor molecules are clonotypical, isolation of their genes requires reverse transcriptase-assisted PCR using primers specific for each different Valpha or Vbeta genes or by the screening of cDNA libraries generated from RNA obtained from each individual T-cell clone. Although feasible, these approaches are laborious and costly. The aim of the present study was to test the application of the non-palindromic adaptor-PCR method as an alternative to isolate the genes encoding the T-cell receptor of an antigen-specific T-cell hybridoma. For this purpose, we established hybridomas specific for trans-sialidase, an immunodominant Trypanosoma cruzi antigen. These T-cell hybridomas were characterized with regard to their ability to secrete interferon-gamma, IL-4, and IL-10 after stimulation with the antigen. A CD3+, CD4+, CD8- interferon-gamma-producing hybridoma was selected for the identification of the variable regions of the T-cell receptor by the non-palindromic adaptor-PCR method. Using this methodology, we were able to rapidly and efficiently determine the variable regions of both T-cell receptor chains. The results obtained by the non-palindromic adaptor-PCR method were confirmed by the isolation and sequencing of the complete cDNA genes and by the recognition with a specific antibody against the T-cell receptor variable beta chain. We conclude that the non-palindromic adaptor-PCR method can be a valuable tool for the identification of the T-cell receptor transcripts of T-cell hybridomas and may facilitate the generation of T-cell receptor transgenic mice.

Oligoclonal T cells are infiltrating the brains of children with AIDS: sequence analysis reveals high proportions of identical beta-chain T-cell receptor transcripts

We have recently described the presence of perivascular CD3+ CD45RO+ T cells infiltrating the brains of children with AIDS. To determine whether these infiltrates contain oligoclonal populations of T cells, we amplified by PCR beta-chain T-cell receptor (TCR) transcripts from autopsy brains of four paediatric patients with AIDS. The amplified transcripts were cloned and sequenced. Sequence analysis of the beta-chain TCR transcripts from all four patients revealed multiple identical copies of TCR beta-chain transcripts, suggesting the presence of oligoclonal populations of T-cells. These TCR transcripts were novel. The presence of oligoclonal populations of T cells in the brains of these four paediatric patients with AIDS suggests that these T cells have undergone antigen-driven proliferation and clonal expansion very likely in situ, in the brains of these AIDS patients, in response to viral or self-antigens. Although the specificity of the clonally expanded beta-chain TCR transcripts remains to be elucidated, none of the beta-chain TCR transcripts identified in this study were identical to those specific for HIV-1 antigens that are currently reported in the GENBANK/EMBL databases. Certain common CDR3 motifs were observed in brain-infiltrating T cells within and between certain patients. Large proportions (24 of 61; 39%) of beta-chain TCR clones from one patient (NP95-73) and 2 of 27 (7%) of another patient (NP95-184-O) exhibited substantial CDR3 homology to myelin basic protein (MBP)-specific TCR derived from normal donors or TCR expressed in the brain of patients with multiple sclerosis (MS) or with viral encephalitis. These two patients (NP95-73 and NP95-184-O) also shared HLA class II with the normal donors and the MS patients who expressed these homologous TCR. Pathologic examination at autopsy of the brains revealed the presence of myelin pallor only in patient NP95-73. T-cell clones identified in the brain of patients NP95-73 and NP95-184-O may recognize MBP or another CNS self antigen and this recognition may be restricted by either DRB1*15 or DQB1*0602 specificities.

Identification of HLA-DQα and -DRβ Residues Associated With Susceptibility and Protection to Epithelial Ovarian Cancer

Substantial evidence has been accumulated suggesting that T cells in patients with epithelial ovarian carcinoma (EOC) exhibit an antigen-driven immune response directed against the tumor cells. In the context of human leukocyte antigen (HLA), this suggests its possible involvement in the disease. Therefore, we examined the distribution of the HLA-DRB1*, -DQA1*, and -DQB1* alleles in 47 patients with EOC and 67 healthy Caucasian women. The frequency of D(70) and E(71) polymorphic residues of the DRB1 alleles was significantly reduced in EOC patients versus controls (pD(70)E(71) = 0.009), suggesting a protective role against the disease. The DQalpha residues R(52) and Y(11)R(55) were increased in the patients (p = 0.008 and 0.012, respectively). Because residues 11 and 55 participate in the formation of pocket 1, they may be functionally important amino acid positions that influence disease susceptibility. The frequency of the DQalpha susceptibility epitope (R(52)Y(11)R(55)) among the DRbetaD(70)E(71)-positive EOC patients was increased when compared with DRbetaD(70)E(71)-positive controls (EOC, 100%; control, 52%; p = 0.028). Among individuals without the DQalpha susceptibility epitope, the distribution of DRbetaD(70)E(71)-positive cases was significantly different between EOC patients and controls (EOC, 0%; control, 60%; p = 0.039). Therefore, it appears that the presence of DQalpha susceptibility elements overrides the protective effect of the DRbetaD(70)E(71) epitope and suggests an interactive relationship between DRbeta and DQalpha epitopes that may be of importance for disease susceptibility. Because positions DRbeta 70,71 and DQalpha 52 have been implicated in immunologic diseases, it is likely that besides being critical for T-cell recognition, they may also play a role in T-cell development and acquisition of the T-cell repertoire.

Substantial proportions of identical β-chain T-cell receptor transcripts are present in epithelial ovarian carcinoma tumors

To determine whether clonally expanded T cells are present in tumor specimens from patients with epithelial ovarian carcinoma (EOC) we amplified by the non-palindromic adaptor PCR (NPA-PCR) or by Vbeta-specific PCR beta-chain T-cell receptor (TCR) transcripts from these tumor specimens. The amplified transcripts were cloned and sequenced. Sequence analysis revealed the presence of substantial proportions of multiple identical copies of beta-chain TCR transcripts, suggesting the presence of clonal expansions of T cells in these patients, which were statistically significant by the binomial distribution in seven of nine patients. Independent amplification in separate experiments of beta-chain TCR transcripts from one patient by either NPA-PCR or by Vbeta-specific PCR, followed by cloning and sequencing, revealed identical clonal expansions irrespectively of the amplification method used. Multiple identical copies of beta-chain TCR transcripts can be derived only by specific antigen-driven proliferation and clonal expansion of the T-cell clones which recognize these antigens. Because of the very large size of the TCR repertoire, the probability of finding by chance multiple identical copies of these transcripts within an independent sample of T cells is negligible. These results demonstrate that T cells infiltrating solid tumor specimens or malignant ascites of patients with EOC contain monoclonal/oligoclonal populations of T cells.

Identical alpha-chain T-cell receptor transcripts are present on T cells infiltrating coronary arteries of human cardiac allografts with chronic rejection

Chronic cardiac allograft rejection is characterized by graft arteriopathy and is a major obstacle of graft survival. We investigated T-cell receptor (TCR) alpha-chain transcripts of T cells infiltrating human epicardial coronary arteries from cardiac allografts with chronic rejection. The non-palindromic adaptor-polymerase chain reaction (NPA-PCR) was used to specifically amplify TCR alpha-chain transcripts from five explanted cardiac allografts with chronic rejection. The amplified products were cloned and sequenced to obtain the entire ValphaJalpha region. Immuno-histochemistry was used to identify the mononuclear cell infiltrates in the coronary arteries. All the five coronary artery specimens exhibited large populations of infiltrating mononuclear cells, which were primarily comprised of T cells and macrophages. In three specimens, high proportions ( approximately 80%) of identical alpha-chain TCR transcripts were detected. In peripheral blood mononuclear cells from a healthy individual, alpha-chain TCR transcripts were unique when compared to each other. Endomyocardial biopsies collected from one patient six months before the allograft was explanted, contained identical alpha-chain TCR transcripts to those found to be clonally expanded in the coronary arteries from this patient. These results indicate that T cells infiltrating the epicardial arteries of cardiac allografts with chronic rejection undergo proliferation and clonal expansion in response to a specific antigen, which very likely is an (allo)antigen(s).

Decreased expression of the CD3zeta chain in T cells infiltrating the synovial membrane of patients with osteoarthritis

Osteoarthritis (OA) is a heterogeneous disease which rheumatologists consider to be noninflammatory. However, recent studies suggest that, at least in certain patients, OA is an inflammatory disease and that patients often exhibit inflammatory infiltrates in the synovial membranes (SMs) of macrophages and activated T cells expressing proinflammatory cytokines. We report here that the expression of CD3zeta is significantly decreased in T cells infiltrating the SMs of patients with OA. The CD3zeta chain is involved in the T-cell signal transduction cascade, which is initiated by the engagement of the T-cell antigen receptor and which culminates in T-cell activation. Double immunofluorescence of single-cell suspensions derived from the SMs from nine patients with OA revealed significantly increased proportions of CD3epsilon-positive (CD3epsilon+) cells compared with the proportions of CD3zeta-positive (CD3zeta+) T cells (means +/- standard errors of the means, 80.48% +/- 3.92% and 69.02% +/- 6.51%, respectively; P = 0.0096), whereas there were no differences in the proportions of these cells in peripheral blood mononuclear cells (PBMCs) from healthy donors (94.73% +/- 1.39% and 93.79% +/- 1.08%, respectively; not significant). The CD3zeta+ cell/CD3epsilon+ cell ratio was also significantly decreased for T cells from the SMs of patients with OA compared with that for T cells from the PBMCs of healthy donors (0.84 +/- 0.17 and 0.99 +/- 0.01, respectively; P = 0.0302). The proportions of CD3epsilon+ CD3zeta+ cells were lower in the SMs of patients with OA than in the PBMCs of healthy donors (65.04% +/- 6.7% and 90.81% +/- 1.99%, respectively; P = 0.0047). Substantial proportions (about 15%) of CD3epsilon+ CD3zeta-negative (CD3zeta-) and CD3epsilon-negative (CD3epsilon-) CD3zeta- cells were found in the SMs of patients with OA. Amplification of the CD3zeta and CD3delta transcripts from the SMs of patients with OA by reverse transcriptase PCR consistently exhibited stronger bands for CD3delta cDNA than for CD3zeta cDNA The CD3zeta/CD3delta transcript ratio in the SMs of patients with OA was significantly lower than that in PBMCs from healthy controls (P < 0.0001). These results were confirmed by competitive MIMIC PCR. Immunoreactivities for the CD3zeta protein were detected in the SMs of 10 of 19 patients with OA, and they were of various intensities, whereas SMs from all patients were CD3epsilon+ (P = 0.0023). The decreased expression of the CD3zeta transcript and protein in T cells from the SMs of patients with OA relative to that of the CD3epsilon transcript is suggestive of chronic T-cell stimulation and supports the concept of T-cell involvement in OA.

Oligoclonal CD4(+) T cell expansions in lung transplant recipients with obliterative bronchiolitis

Obliterative bronchiolitis (OB) is a dreaded and frequent complication of lung transplantation with a poorly understood immunopathogenesis. To further evaluate disease mechanisms, we used T cell antigen receptor (TCR) beta-chain variable region RNase protection assays, after polymerase chain reaction amplification of TCR cDNA, to quantitate circulating CD4(+) and CD8(+) repertoires of transplant recipients with OB or no evidence of rejection (NER). All six recipients with OB had markedly abnormal CD4 expansions (2.5 +/- 0.5 expansions/recipient) attributable to oligoclonal proliferations. Only two of six recipients with NER had a single, much lesser, CD4(+) abnormality each (p < 0.01). Moreover, one of these patients developed OB shortly thereafter, and the other NER abnormality may have predated transplantation. In contrast, CD8(+) expansions were common in both recipient populations. Findings of CD4(+) expansions had 100% sensitivity and 80% specificity for the presence or imminent development of OB. These data suggest proliferations of CD4(+) T cells are important in OB pathogenesis, and these are most likely part of a major histocompatibility complex Class II-dependent process of indirect alloantigen presentation. These CD4(+) clones are likely to have facultative helper functions for the multiple and diverse immune processes that have been implicated in OB. Furthermore, the close association of CD4(+) expansions with OB raises possibilities of development of novel diagnostic and therapeutic approaches.

Oligoclonal T cell expansion in the skin of patients with systemic sclerosis

Fibrosis, microvascular fibroproliferative alterations, and autoantibody production are the main features of systemic sclerosis (SSc), and all of them can be explained by cytokine production by activated T cells. However, little is known about the role of T cells in the pathogenesis of SSc, and there is no information on the Ag(s) that elicits such activation. To determine whether T cells infiltrating the skin biopsies of patients with SSc are oligoclonal, beta-chain TCR transcripts from T cells infiltrating the skin of five patients with SSc of recent onset were amplified by either Vbeta-specific PCR or nonpalindromic adaptor PCR. The resulting PCR products were subsequently cloned and sequenced. High proportions of identical beta-chain TCR transcripts ranging from 43 to 90% of those sequenced were found in five patients, strongly suggesting the presence of oligoclonal T cells in these infiltrates. A dominant T cell clone was found to be clonally expanded in skin biopsies obtained from a single patient with SSc at three different times (0, 8, and 13 mo earlier) and from three different skin regions. beta-chain TCR transcripts from PBMC from normal donors (methodological control) were unique when compared with each other, typical for polyclonal populations of T cells. The finding of oligoclonal T cells infiltrating the skin of patients with SSc suggests that these T cells have undergone proliferation in situ in the skin and clonal expansion in response to as yet unidentified Ag(s). These results suggest that T cells are involved in the pathogenesis of the disease.

TCR usage in naive and committed alloreactive cells: implications for the understanding of TCR biases in transplantation

The direct pathway of allorecognition is involved in acute allograft rejection and is characterised by TCR-mediated recognition of the MHC framework; this is thought to occur in a peptide-dependent but not peptide-specific manner. In contrast, the indirect pathway is restricted to the recipient's own MHC molecules and prevails in chronic rejection. In this pathway, the peptide has a major influence on the TCR recognition and selects alloreactive T cells with altered TCR Vbeta usage. However, qualitative analysis of Vbeta usage alone might limit our understanding of alloreactivity. The advantages of a combined quantitative assessment of Vbeta mRNA usage are discussed.

APOPTOSIS IN CHRONIC REJECTION OF HUMAN CARDIAC ALLOGRAFTS1

BACKGROUND

We investigated the role of apoptosis (programed cell death) in the pathogenesis of chronic rejection.

METHODS

Epicardial coronary arteries from cardiac allografts with chronic rejection were examined for apoptosis by the TUNEL assay. Double labeling was carried out using anti-CD3, anti-CD68, and anti-von Willenbrand factor (vWF) monoclonal antibodies. Additional immunostaining was carried using anti-Fas, anti-Fas-L, and anti-Bcl-2 monoclonal antibodies. Apoptosis-associated oligonucleosomal DNA degradation was assessed by DNA agarose gel electrophoresis. The transcription level of apoptosis-related caspase genes were determined using microarrays.

RESULTS

Apoptotic cells (TUNEL+) were detected within the arterial wall and in perivascular areas. Double labeling demonstrated that apoptotic cells included T cells (CD3+), monocyte/macrophages (CD68+), and vascular endothelial cells (VWF+). Numbers and densities of TUNEL+ cells did not correlate with the degree of arterial stenosis. Apoptosis-associated oligonucleosomal DNA degradation was assessed by agarose gel electrophoresis of DNA, which showed DNA fragments of approximately 180 bp and multimers thereof (DNA laddering gel), which are characteristic for DNA fragmentation in apoptotic cells. Microarray analysis demonstrated that the apoptosis related caspases 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, were all transcribed (caspases 8, 9, and 10 were highly up-regulated). These results are consistent with the involvement of apoptosis in chronic rejection. Immunoreactivity for Fas/Fas-L was present at the sites of apoptotic cells. Immunoreactivity for Bcl-2 was present in areas with very few apoptotic cells.

CONCLUSIONS

Apoptotic cells include T cells, monocyte/macrophages, and endothelial cells. Apoptosis, likely through the Fas/Fas-L system, is involved in the pathogenesis of chronic rejection in cardiac allografts.