Quantitative analysis of the usage of human T cell receptor alpha and beta chain variable regions by reverse dot blot hybridization

Repertoire analysis of memory T-cell receptors in Japanese patients with inflammatory bowel disease

Background and Aim

The T‐cell receptor (TCR) repertoire was assessed in response to various antigens and was considered to be associated with the pathogenesis of inflammatory bowel disease (IBD). Thus, we performed TCR repertoire analysis to examine the pathology of IBD from changes in the TCR repertoire of memory T cells in the intestinal lamina propria mononuclear cells (LPMCs) and peripheral blood mononuclear cells (PBMCs) of patients with IBD.

Methods

LPMCs in the surgical specimens and PBMCs were isolated from 12 patients with IBD (5 patients with ulcerative colitis [UC] and 7 patients with Crohn's disease [CD]). PBMCs were collected from 10 healthy individuals as controls. Comprehensive TCR sequence analyses of adaptor‐ligation polymerase chain reaction (PCR) products were performed using MiSeq.

Results

The diversity of TCR‐α and TCR‐β in PBMCs was significantly lower in patients with IBD than that in controls (P = 0.00084 and 0.0013, respectively). Comparisons of TCR diversity in LPMCs and PBMCs between CD and UC showed that the diversity in LPMC was not affected by diseases, whereas that in PBMCs was significantly lower in CD than in UC (P = 0.045 and 0.049, respectively). Some TCR clones may have shown a specific increase or decrease in CD and UC, and many clones were common to both LPMCs and PBMCs in the same patients.

Conclusion

The diversity of TCR clones in LPMCs and PBMCs in patients with IBD was significantly lower than that of PBMCs in controls. TCR diversity in PBMCs was particularly low in patients with CD.

A new method for quantitative analysis of the T cell receptor V region repertoires in healthy common marmosets by microplate hybridization assay

The common marmoset, Callithrix jacchus, is one of the smallest primates and is increasingly used for an experimental nonhuman primate model in many research fields. Analysis of T cell receptor (TCR) repertoires is a powerful tool to investigate T cell immunity in terms of antigen specificity and variability of TCR expression. However, monoclonal antibodies specific for many TCR Vα or Vβ chains have not been created. We have recently identified a large number of TCRα chain variable (TRAV) and TCRβ chain variable (TRBV) sequences from a cDNA library of common marmosets. The purpose of this study is to develop a new method for analysis of TCR repertoires in the common marmoset using this sequence information. This method is based on a microplate hybridization technique using 32 TRAV-specific and 32 TRBV-specific oligoprobes following an adaptor-ligation PCR. This enables the easy quantitation of the respective TRAV and TRBV expression levels. No cross-hybridization among specific-oligoprobes and very low variances in repeated measures of the same samples was found, demonstrating high specificity and reproducibility. Furthermore, this method was validated by an antihuman Vβ23 antibody which specifically bound to marmoset Vβ23. Using this method, we analyzed TCR repertoires from various tissue samples (PBMCs, spleen, lymph node and thymus) and isolated T cell subpopulations (CD4+CD8+, CD4+CD8− and CD4−CD8+) from the thymus of 10 common marmosets. Neither tissue-specific nor T cell subpopulation-specific differences was found in TRAV and TRBV repertoires. These results suggest that, unlike mice, TCR repertoires in the common marmoset are not affected by endogenous superantigens and are conserved among individuals, among tissues, and among T cell subpopulations. Thus, TCR repertoire analysis with high specificity and reproducibility is a very useful technique, with the potential to replace flow cytometric analysis using a panel of TRV-specific antibodies, many of which remain unavailable.

Germ line-governed recognition of a cancer epitope by an immunodominant human T-cell receptor

CD8(+) T-cells specific for MART-1-(26-35), a dominant melanoma epitope restricted by human leukocyte antigen (HLA)-A*0201, are exceptionally common in the naive T-cell repertoire. Remarkably, the TRAV12-2 gene is used to encode the T-cell receptor alpha (TCRalpha) chain in >87% of these T-cells. Here, the molecular basis for this genetic bias is revealed from the structural and thermodynamic properties of an archetypal TRAV12-2-encoded TCR complexed to the clinically relevant heteroclitic peptide, ELAGIGILTV, bound to HLA-A*0201 (A2-ELA). Unusually, the TRAV12-2 germ line-encoded regions of the TCR dominate the major atomic contacts with the peptide at the TCR/A2-ELA interface. This "innate" pattern of antigen recognition probably explains the unique characteristics and extraordinary frequencies of CD8(+) T-cell responses to this epitope.

Role of TRPV3 in immune response to development of dermatitis

Background

Recently, it has been reported that the Gly573Ser substitution of transient receptor potential V3 (TRPV3) leads to increased ion-channel activity in keratinocytes. Our previous studies have indicated that the spontaneous hairless and dermatitis phenotypes of DS-Nh mice, which were newly established as an animal model of atopic dermatitis (AD), are caused by TRPV3^Gly573Ser. Although this substitution causes hairlessness in several kinds of rodents, in our investigations, dermatitis developed in only a few animals. Here, we generated NC/Nga-Nh mice to elucidate the role of TRPV3^Gly573Ser in NC/Nga mice, which is one of the most studied animal models of AD.

Methods

To establish and validate the new AD animal model, NC/Nga-Nh mice were generated using NC/Nga and DS-Nh mice, and their clinical features were compared. Next, T-cell receptor (TCR) Vβ usage in splenocytes, evaluation of bacterial colonization, and serological and histological analyses were carried out. Finally, repeated-hapten-application dermatitis was induced in these mice.

Results

NC/Nga-Nh mice did not develop spontaneous dermatitis, whereas DS-Nh mice displayed this phenotype when maintained under the same conditions. Serological analysis indicated that there really was a phenotypic difference between these mice, and TCR repertoire analysis indicated that TCRVβ haplotypes played an important role in the development of dermatitis. Artificial dermatitis developed in DS and NC/Nga-Nh mice, but not in DS-Nh and NC/Nga mice. Histological and serological analyses indicated that mouse strains were listed in descending order of number of skin mast cells: DS-Nh > DS ≈ NC/Nga-Nh > NC/Nga, and serum IgE levels were increased after 2,4,6 trinitrochlorobenzene application in these mice. Serum IgE level in DS-Nh mice was lower than that mesured in other strains.

Conclusion

Our results confirm the contribution of the TRPV3^Gly573Ser gene to the development of repeated hapten dermatitis, but not spontaneous dermatitis in NC/Nga mice.

Association of T-cell receptor Vbeta haplotypes with dry skin in DS-Nh mice

BACKGROUND

Although dry skin and T cell-dependent disease exacerbation are characteristic features of atopic dermatitis (AD), the involvement of T cells in the development of dry skin remains unclear.

AIMS

We aimed to elucidate the role of T cells in the development of dry skin in DS-Nh mice as a model for AD, and to evaluate this skin condition pharmacologically.

METHODS

We prepared DS-Nh mice harbouring a T-cell receptor (TCR)Vbeta(a) haplotype with a central deletion in the TCRBV gene segments, and mice harbouring a TCRVbeta(b) haplotype without any deletion. We analysed the TCRVbeta chain usage and cytokine response to antimouse CD3 monoclonal antibodies in the splenocytes from the two mouse substrains. Transepidermal water loss (TEWL) was measured, and histochemical examination of these mice was carried out. Finally, a pharmacological analysis using loratadine was also performed to evaluate the features of spontaneous dry skin in DS-Nh mice as a model of AD.

RESULTS

Although the deletion of TCRBV gene segments in the TCRVbeta(a) haplotype yielded different representations of each TCRVbeta mRNA, this deletion did not evoke distinct cytokine profiles in the splenocytes compared with those of mice with the TCRVbeta(b) haplotype. Furthermore, our results indicated that the onset of dry skin occurred earlier in mice with TCRVbeta(b) than in those with TCRVbeta(a). Pharmacologically, AD-like dry skin in DS-Nh with TCRVbeta(b) mice is susceptible to an H1 blocker.

CONCLUSIONS

A specific lymphocyte subpopulation bearing T-cell receptors may be responsible for loratadine-responsive dermatitis in DS-Nh mice.

Impact of T-cell receptor Vbeta haplotypes on the development of dermatitis in DS-Nh mice: synergistic production of interleukin-13 caused by staphylococcal enterotoxin C and peptide glycans from Staphylococcus aureus

Although the pathogenic role of interleukin-13 (IL-13) is a key for atopic dermatitis (AD), the mechanism of IL-13 production in AD remains unclear. To investigate the role of the T-cell receptor Vbeta (TCR Vbeta) haplotype in the development of dermatitis and the production of IL-13 in the naturally occurring dermatitis model by staphylococcal enterotoxin C (SEC)-producing Staphylococcus aureus, we raised DS-Nh mice harbouring the TCR Vbeta(a) haplotype with a central deletion in the TCRBV gene segments, including TCR Vbeta8S2. Observation and histopathological analysis of the two mouse substrains with spontaneous dermatitis indicated that later onset and weaker severity of AD-like dermatitis were identified in mice with TCR Vbeta(a) compared to those with TCR Vbeta(b). Immunohistochemical examination revealed the infiltration of a large number of CD4-bearing T cells in the skin lesions in mice with TCR Vbeta(b) but not in those with TCR Vbeta(a). Interestingly, much lower levels of serum IL-13 were detected in mice with the TCR Vbeta(a) than in those with the TCR Vbeta(b) haplotype. In vitro, synthetic ligands (Pam(2)CSK4) of toll-like receptor 2 (TLR2) synergistically produced IL-13 with SEC in splenocytes of mice with TCR Vbeta(b) but not of those with TCR Vbeta(a), and natural killer T cells were essential for this synergism. Our findings suggested that this TCR Vbeta-haplotype-dependent synergism with TLR2 plays an important role in the development of AD-like dermatitis in DS-Nh mice.

An improved methodology to detect human T cell receptor beta variable family gene expression patterns

Comprehensive gene expression analysis of the T cell receptor repertoire of an individual can be very useful in evaluating the immune response in a variety of conditions. Antibody-based analysis methods can detect approximately 60% of the human T cell receptor beta variable (TCRBV) proteins, while gene expression analysis, primarily through employment of the polymerase chain reaction (PCR), has had somewhat greater success in the detection of additional TCRBV families. Many of these previous PCR methods, however, have been unable to detect all 91 alleles of the human TCRBV genes. This is primarily due to either deficiencies in the amplification of all of the variable beta families, subfamilies, and alleles, or the prior lack of a systematic classification of the TCR variable family gene segment sequences. We describe here a real-time reverse transcription polymerase chain reaction-based method, which allows efficient automation and integration of amplification, detection, and analysis with sequence-specific detection of all T cell receptor beta variable gene families, subfamilies, and alleles. This method, which in itself contributes significant improvements over existing technologies through its comprehensiveness and efficiency, also functions independently of variables such as sample source and sample processing and has the ability to run on multiple real-time PCR platforms, affording one the implementation of personal preferences.

Simplified fluorescent multiplex PCR method for evaluation of the T-cell receptor V beta-chain repertoire

RATIONALE

Evaluation of the T-cell receptor (TCR) V beta-chain repertoire by PCR-based CDR3 length analysis allows fine resolution of the usage of the TCR V beta repertoire and is a sensitive tool to monitor changes in the T-cell compartment. A multiplex PCR method employing 24 labeled upstream V beta primers instead of the conventionally labeled downstream C beta primer is described.

METHOD

RNA was isolated from purified CD4 and CD8 T-cell subsets from umbilical cord blood and clinical samples using TRI reagent followed by reverse transcription using a C beta primer and an Omniscript RT kit. The 24 V beta primers were multiplexed based on compatibility and product sizes into seven reactions. cDNA was amplified using 24 V beta primers (labeled with tetrachloro-6-cardoxyfluorescein, 6-carboxyfluorescein, and hexachloro-6-carboxyfluorescein), an unlabeled C beta primer, and Taqgold polymerase. The fluorescent PCR products were resolved on an automated DNA sequencer and analyzed using the Genotyper 2.1 software.

RESULTS

V beta spectratypes of excellent resolution were obtained with RNA amounts of 250 ng using the labeled V beta primers. The resolution was superior to that obtained with the labeled C beta primer assay. Also the numbers of PCRs were reduced to 7 from the 12 required in the C beta labeling method, and the sample processing time was reduced by half.

CONCLUSION

The method described for T-cell receptor V beta-chain repertoire analysis eliminates tedious dilutions and results in superior resolution with small amounts of RNA. The fast throughput makes this method suitable for automation and offers the feasibility to perform TCR V beta repertoire analyses in clinical trials.

The presence and longevity of peripherally expanded donor-derived TCRalphabeta+ mature T lymphocyte clones after allogeneic bone marrow transplantation for adult myeloid leukemias

There are two major pathways for T-cell regeneration after allogeneic bone marrow transplantation; thymus-dependent T-cell differentiation of T-cell progenitors, and peripheral expansion of mature T cells in the graft. In order to learn to what extent the peripheral expansion of donor-derived mature T lymphocytes contributes to reconstitution of the TCRalphabeta+ T-cell repertoire after allogeneic bone marrow transplantation for adult myeloid leukemias, we pursued the fate of donor-derived T-cell clones using the amino-acid sequences of the complementarity-determining region 3 (CDR3) of the TCR-beta chain as a clonal marker. Clonal expansion of TCRalphabeta+ T lymphocytes with specific TCRBV subfamilies was identified in donor blood. Identical T-cell clones were not found in blood from recipients before transplantation. The donor-derived T-cell clones were identified in the circulating blood from recipients a few months after allogeneic bone marrow transplantation, and they remained in the blood for 18 months after transplant in two recipients, and for 56 months in one. These results suggest that the peripheral expansion of mature T lymphocytes in the graft makes a significant contribution to post-transplant T-cell regeneration during the early period of transplantation in humans, and that mature T cells can survive in recipients for several years. Further investigation will be required to explore which antigens drive the expansion of T-cell clones in donors and recipients, and the mechanisms of maintaining homeostatic balance between the thymus-dependent pathway and the peripheral expansion of mature T cells in post-transplant T-cell regeneration.

DS-Nh as an experimental model of atopic dermatitis induced by Staphylococcus aureus producing staphylococcal enterotoxin C

DS-Nh mice raised under conventional conditions spontaneously develop dermatitis similar to human atopic dermatitis (AD), which is associated with staphylococcal infection. In the present study, we show that Staphylococcus aureus producing staphylococcus exotoxin C (SEC) was recovered from the culture of the skin lesions of DS-Nh mice with AD-like dermatitis and that the serum levels of anti-SEC antibodies from these mice were elevated. We describe here how to promote experimental AD by epicutaneous injection with SEC-producing S. aureus to DS-Nh mice. In order to assess the role of SEC in the pathogenesis of AD, the mitogenic activity, TCRBV repertoire analysis and the production of IL-4 and IFN-gamma from spleen mononuclear cells (MNC) from DS-Nh stimulated by SEC were compared with those due to SEA, SEB and TSST. The weakest was the mitogenic activity of SEC, and higher IL-4 responses and lower IFN-gamma responses to SEC showed correlation with TCRBV8S2-positive T cells, which were selectively stimulated by SEC. We also demonstrate that SEC-producing S. aureus was able to survive in DS-Nh after intradermal injection. These results suggest a possible role for SEC in the pathogenesis of AD through host-S. aureus relationships.

Relation of streptococcal pyrogenic exotoxin C as a causative superantigen for Kawasaki disease

We previously reported that the frequency of TCRBV2 and TCRBV6S5-bearing T-cells was high in patients in the acute phase of Kawasaki disease (KD) and that streptococcal pyrogenic exotoxin C (SPE-C) was a potent stimulator of these TCRBV-bearing T-cells. To further elucidate the pathogenesis of KD, we examined the T-cell receptor (TCR) repertoire, human leukocyte antigen (HLA)-DRB1 genotype, and antibody responses to recombinant(r) SPE-C in patients with KD. We also performed in vitro stimulation with rSPE-A and rSPE-C of peripheral blood mononuclear cells from healthy donors and characterized the reacting T-cells. The percentage of T-cells bearing TCRBV2 and TCRBV6S5 was high in patients in the acute stage of KD. rSPE-C stimulation of PBMC from healthy donors induced expansion of TCRBV2 and TCRBV6S5-bearing T-cells. Furthermore, serum levels of anti-SPEC antibodies, which did not display antimitogenic activity, were higher in patients with acute KD than in age-matched controls. The frequencies of the DRB1*04051, 0406, and 0901 were high, whereas that of the DRB1*1101 was low among patients with KD as compared with the healthy adults.

Distinct TCRAV and TCRBV repertoire and CDR3 sequence of T lymphocytes clonally expanded in blood and GVHD lesions after human allogeneic bone marrow transplantation

Acute graft-versus-host disease (GVHD) is a disorder involving the skin, gut and liver that is caused by mismatches of major and/or minor histocompatibility antigens between the HLA-identical donor and recipient. If T lymphocytes infiltrating GVHD lesions recognize antigens expressed in these organs, T cell clones should expand in inflammatory tissues. We previously reported that recipients of allogeneic bone marrow grafts have clonally expanded TCRalphabeta(+) T lymphocytes soon after transplantation, which leads to a skew of TCR repertoires. To establish whether or not the same antigens cause clonal expansion of T lymphocytes in both blood and GVHD tissues, we examined the usage of TCR alpha and beta chain variable regions (TCRAV and TCRBV) and determined the complementarity-determining region 3 (CDR3) of T lymphocytes clonally expanded in circulating blood and GVHD lesions. We found that the repertoires and CDR3 diversity of TCRAV and TCRBV differed between the GVHD lesions and circulating blood, suggesting the selective recruitment of antigen-specific T cells into GVHD tissues. We also found that the usage of TCRAV and TCRBV by the clonally expanded T lymphocytes and their CDR3 sequences differed between the GVHD tissues and blood. These results suggest that the antigen specificity of TCRalphabeta(+) T lymphocytes clonally expanded in blood and GVHD lesions is different.

Identification of the T cell clones expanding within both CD8+CD28+ and CD8+CD28− T cell subsets in recipients of allogeneic hematopoietic cell grafts and its implication in post-transplant skewing of T cell receptor repertoire

We have previously reported that skewed repertoires of T cell receptor-beta chain variable region (TCRBV) and TCR-alpha chain variable region (TCRAV) are observed at an early period after allogeneic hematopoietic cell transplantation. Furthermore, we found that T lymphocytes using TCRBV24S1 were increased in 28% of the recipients of allogeneic grafts and an increase of TCRBV24S1 usage was shown to result from clonal expansions. Interestingly, the arginine residue was frequently present at the 3' terminal of BV24S1 segment and was followed by an acidic amino acid residue within the CDR3 region. These results suggest that these clonally expanded T cells are not randomly selected, but are expanded by stimulation with specific antigens. This study was undertaken to elucidate the mechanisms of the post-transplant skewing of TCR repertoires. Since the CD8(+)CD28(-)CD57(+) T cell subset has been reported to expand in the peripheral blood of patients receiving allogeneic hematopoietic cell grafts, we examined the TCRAV and TCRBV repertoires of the CD8(+)CD28(-) T cell and CD8(+)CD28(+) T cell subsets, and also determined the clonality of both T cell populations. In all three recipients examined, the CD8(+)CD28(-) T cell subset appeared to define the post-transplant TCR repertoire of circulating blood T cells. Moreover, the CDR3 length of TCRBV imposed constraints in both CD8(+)CD28(-) T cell and CD8(+)CD28(+) T cell subsets. The DNA sequences of the CDR3 region were determined, and the same clones were identified within both CD8(+)CD28(-) and CD8(+)CD28(+) T cell subsets in the same individuals. These results suggest that the clonally expanded CD8(+)CD28(-) T cells after allogeneic hematopoietic cell transplantation derive from the CD8(+)CD28(+) T cell subset, possibly by an antigen-driven mechanism, resulting in the skewed TCR repertoire.

Oligoclonal expansion of CD4(+)CD28(-) T lymphocytes in recipients of allogeneic hematopoietic cell grafts and identification of the same T cell clones within both CD4(+)CD28(+) and CD4(+)CD28(-) T cell subsets

Recipients of allogeneic bone marrow grafts have clonally expanded CD8(+)CD28(-) T lymphocytes during the early period after transplantation, which leads to skewing of T cell receptor (TCR) repertoires. Here, we have addressed the question of whether clonal expansion of CD28(-) T cells is also observed in CD4(+) T lymphocytes after human allogeneic hematopoietic cell transplantation. We found that the fraction of T cells lacking CD28 expression in the CD4(+) subset was increased after transplantation, and expanded CD4(+)CD28(-) T lymphocytes carrying certain TCRBV subfamilies showed limited TCR diversity. In order to further study the ontogeny of CD4(+)CD28(-) T cells, we analyzed the complementarity-determining region 3 (CDR3) of the TCR-beta chain of CD4(+)CD28(+) and CD4(+)CD28(-) cells. We identified the same T cell clones within both CD4(+)CD28(-) and CD4(+)CD28(+) T cell subsets. These results suggest that both subsets are phenotypic variants of the same T cell lineage.

Extensive clonal expansion of T lymphocytes causes contracted diversity of complementarity-determining region 3 and skewed T cell receptor repertoires after allogeneic hematopoietic cell transplantation

We previously described skewed repertoires of the T cell receptor-beta chain variable region (TCRBV) and the TCR-alpha chain variable region (TCRAV) soon after allogeneic hematopoietic cell transplantation. To determine the characteristics of skewed TCRBV after transplantation, we examined the clonality of T lymphocytes carrying skewed TCRBV subfamilies and determined the CDR3 sequences of expanded T cell clones. In all 11 recipients examined, TCR repertoires were skewed, with an increase of certain TCRBV subfamilies that differed among individuals. In nine of 11 patients, clonal/oligoclonal T cell expansion was observed, although the expanded T cells were not necessarily oligoclonal. The extent of expansion after transplantation appeared to predict clonality. The arginine (R)-X-X-glycine (G) sequence was identified in clonally expanded T cells from four of five recipients examined, and glutamic acid (E), aspartic acid (D) and alanine (A) were frequently inserted between R and G. These results suggest that T lymphocyte expansion may result from the response to antigens widely existing in humans, and that the extensive clonal expansion of a limited number of T cells leads to contracted CDR3 diversity and post-transplant skewed TCR repertoires.

Delayed recovery of CDR3 complexity of the T-cell receptor-beta chain in recipients of allogeneic bone marrow transplants who had virus-associated interstitial pneumonia: monitor of T-cell function by CDR3 spectratyping

BACKGROUND

In the T-cell receptor (TCR)-beta chain, complementary-determining region 3 (CDR3) contains specific peptide sequences essential for recognition. Diversity of this region is considered to contribute to immunocompetence in humans.

OBJECTIVE

The purpose of this study was to define the process of reconstitution of CDR3 complexity of the TCR-beta chain after allogeneic bone marrow transplantation and to investigate the association between host immunocompetence and CDR3 complexity.

METHODS

Diversity of the CDR3 region of the TCR-beta chain was examined by CDR3 size distribution analysis with the use of an automated DNA sequencer.

RESULTS

Reconstitution of the alphabeta T-cell repertoire and CDR3 diversity was incomplete for at least 2 months after bone marrow transplantation. Delayed reconstitution of T-cell diversity was more marked in immunocompromised hosts. Unlike the situation in patients who received allogeneic bone marrow grafts, the recovery of CDR3 complexity was almost perfect by 2 months after transplantation in patients who received allogeneic blood stem cells. Clonal expansion of alphabeta T cells after allogeneic bone marrow transplantation was readily detected by CDR3 size spectratyping analysis.

CONCLUSION

PCR-based CDR3 size spectratyping may be a useful tool for clinically monitoring immune reconstitution after allogeneic bone marrow transplantation.

Restricted usage of T-cell receptor alpha-chain variable region (TCRAV) and T-cell receptor beta-chain variable region (TCRBV) repertoires after human allogeneic haematopoietic transplantation

We analysed T-cell receptor alpha-chain variable region (TCRAV) and T-cell receptor beta-chain variable region (TCRBV) repertoires in peripheral blood mononuclear cells (PBMCs) from 34 recipients of allogeneic bone marrow transplantation (allo-BMT), seven of allogeneic peripheral blood stem cell transplantation and 19 of autologous peripheral blood stem cell transplantation using the quantitative microplate hybridization assay. TCR usage skewed at an early period (6-7 weeks) after BMT. The change was more apparent in allogeneic recipients than in autologous recipients. In particular, a predominant increase was detected in the frequency of VA1-4 (26%, 11 of 41 recipients), VA3-1 (32%) and VB24-1 (28%). Interestingly, acidic amino acid residues frequently followed the arginine residue in complementarity-determining region 3 of BV24S1. We further examined the extent of skew using samples obtained at serial time points after transplantation. The normalization of skewed repertoires occurred over a long period of time (> 8 years). There was a significant difference in the rate of normalization of skewed TCR repertoires between adult and child recipients (P < 0.05). The results suggest that these T cells may have expanded in response to allogeneic antigens, such as miHA (minor histocompatibility antigen), and that altered repertoires are eventually normalized by T-cell regeneration via a thymic-dependent pathway in children.

Identification of isoform-specific T-cell epitopes in the major timothy grass pollen allergen, Phl p 5

BACKGROUND

The involvement of CD4+ T cells in the pathophysiology of atopic disease is well established.

OBJECTIVE

To gain further insight into the activation requirements for allergen-specific T cells, we characterized epitope specificity, HLA restriction and T-cell receptor (TCR) usage for T cells specific to Phl p 5, the group 5 major allergen of the grass Phleum pratense.

METHODS

To identify the T-cell epitopes of Phl p 5, three Phl p 5-specific T-cell lines (TCLs) and 15 T-cell clones (TCCs) generated from the peripheral blood of three grass-allergic patients were tested with recombinant truncated Phl p 5a fragments and synthetic Phl p 5b peptides representing these two different recombinant Phl p 5 isoallergens. Additional activation experiments with HLA-subtyped antigen-presenting cells and flow cytometry analysis with TCR V-specific mAb were performed to further characterize the activation requirements for Phl p 5-specific TCCs.

RESULTS

At least nine distinct T-cell specificities were identified and the T-cell epitopes recognized differed considerably among the three patients. Most of the epitopes found were isoform-specific, whereas three epitopes were shared between Phl p 5a and 5b. Several human leucocyte antigen (HLA) class II molecules were involved in the recognition of Phl p 5. Different HLA restriction specificities were even found among TCCs specific to the same epitope region. All TCCs were TCR-alpha/beta positive, and an overrepresentation of TCR Vbeta 3.1+ clones among TCCs specific to Phl p 5 appear to exists as 31% (4/13) of the TCCs expressed TCR Vbeta 3.1 (compared with 5% TCR Vbeta 3.1+ T cells in human peripheral blood) with no correlation with epitope specificity or HLA restriction.

CONCLUSION

The T-cell reactivity of the three grass-allergic patients investigated shows that isoallergen-specific T-cell epitopes are found throughout the peptide backbone of Phl p 5a and Phl p 5b, and dominant T-cell epitopes of Phl p 5 were not identified. This indicates that a mixture of at least full-length rPhl p 5a and rPhl p 5b may be required to target the total Phl p 5-specific T-cell response of atopic patients.

Polyclonal expansion of TCRBV2- and TCRBV6-bearing T cells in patients with Kawasaki disease

We examined T-cell receptor (TCR) usage, cytokine production and antibody responses to superantigens in patients with Kawasaki disease (KD) to facilitate a better understanding of the immunopathogenesis of KD. The mean percentage of VB2- or VB6. 5-bearing T cells in peripheral blood mononuclear cells (PBMC) of patients with acute-phase KD was significantly higher than that of patients in the convalescent phase of KD or in healthy donors. Expansion of VB2- or VB6.5-bearing T cells was polyclonal because DNA sequences in the complementarity determining region 3 of VB2- and VB6.5-positive cDNA clones were all different from each other. The plasma levels of interleukin (IL)-1beta, IL-2, IL-6, IL-8, IL-10, interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha) and granulocyte colony-stimulating factor (G-CSF) were elevated in the acute phase of KD. We previously reported that streptococcal pyrogenic exotoxin C (SPEC) was a potent stimulator of VB2- and VB6.5-positive T cells and, furthermore, serum levels of anti-SPEC antibodies were significantly higher in patients with acute and convalescent KD than in age-matched controls. The results of the present study, together with those of our previous report, suggest that SPEC induces activation and polyclonal expansion of VB2- and VB6.5-positive T cells, and that SPEC-induced activation of T cells may lead to the pathogenesis of KD.

Rapid screening of T-cell receptor (TCR) variable gene usage by multiplex PCR: application for assessment of clonal composition

The selection of various T-cell receptor (TCR) gene families and complex rearrangements during intra-thymic differentiation provide the basis for the expression of antigen specificity by mature T cells. TCR beta variable (TCRBV) transcripts can be identified by RT-PCR, but multiple reactions are required to detect all genes of the TCRBV subfamilies. We describe here a multiplex PCR method that amplifies 46 functional genes comparing 23 TCRBV families in 5 reactions where each reaction contains 4 to 7 specific primers together with a single fluorescence-tagged TCR beta constant region primer. Between 8 and 10 distinct subtypes within each of the 23 TCRBV families can be identified by analysis of the CDR3 length. Multiplex PCR products isolated from agarose gels can be subjected to direct sequencing for confirmation and definitive clonotyping if necessary. The data illustrated here show that the multiplex PCR technique is useful for screening TCRBV usage and can be easily adapted for analysis of clonal composition in T-cell populations.

Analysis of TCRAV and TCRBV repertoires in healthy individuals by microplate hybridization assay

We have developed an adaptor ligation PCR-based microplate hybridization assay (MHA) for analysis of T cell receptor alpha chain variable region (TCRAV) and T cell receptor beta chain variable region (TCRBV) repertoires. Forty three TCRAV and thirty eight TCRBV-specific probes were immobilized onto microplate wells in water-soluble carbodiimide. After hybridization of 5'-biotinylated PCR products, quantitative ELISA was carried out and followed by automated colorimetric reading. The conditions for immobilization and hybridization were optimized using representative TCRBV-specific probes. The sensitivity of MHA allows us to detect as low as 40 pg of biotinylated PCR products. The frequencies of individual V segments obtained by MHA were consistent with those obtained by FACS analysis and reverse dot blot assays. Analysis of the entire TCRAV and TCRBV repertoires could be done using a single 96-well plate, and completed in less than 6 h. Simplicity and reproducibility of this method make it suitable for routine laboratory use. The expression of TCRAV and TCRBV segments was next studied in peripheral blood mononuclear cells (PBMC) of 14 healthy donors using the newly developed MHA method. TCRAV8S1, TCRAV23S1, TCRBV2S1, TCRBV3S1, TCRBV4S1, and TCRBV6S5 were highly expressed in PBMC. Further, the TCRAV repertoires among individuals were less variable compared to the TCRBV repertoires. Interestingly, considerable variations in the expression levels of BV3S1, BV4S1, and BV17S1 were observed among individuals. One polymorphic site was found at the coding region of BV4S1, and there were two alleles. These results suggest that variable expression among individuals may be associated with unknown allelic polymorphism in coding and/or regulatory regions of these TCRBV segments, or with disparity in HLA genes.