Nearly identical T-cell receptor V-gene usage at birth in two cohorts of distinctly different ethnic origin: influence of environment in the final maturation in the adult

Age-related changes in the TRB and IGH repertoires in healthy adult males and females

A diverse immune repertoire is capable of recognizing the enormous universe of foreign antigens encountered over life. Aging has a profound impact on the immune repertoires. However, whether continuous age-related changes in the immune repertoires differ between sexes is unclear. In this study, the characteristics of immune repertoires stratified by sex during aging are deciphered by analyzing T-cell receptor β-chain (TRB) and immunoglobulin heavy chain (IGH) sequences in 361 healthy adults. A similar change was observed between males and females across their lifespan, whereas age-subgroup analysis revealed sex-specific signatures in TRB and IGH repertoires. In regard to TRB, in males, repertoire richness and evenness increases slightly before the age of 32 years and 45 years respectively, and decreases sharply thereafter. Intriguingly, in females, they decrease significantly until around the age 57 years old, and subsequently undergo a stable stage up to the age of 83 years. Although IGH repertoire evenness increases significantly with age in both sexes, richness decreases significantly with age in males but remains stable in females. Moreover, average length of IGH CDR3 increases with age. In conclusion, these findings provide fundamental insights into the mechanisms underlying sex differences in adaptive immunity.

Sex bias in MHC I-associated shaping of the adaptive immune system

HLA associations, T cell receptor (TCR) repertoire bias, and sex bias have independently been shown for many diseases. While some immunological differences between the sexes have been described, they do not fully explain bias in men toward many infections/cancers, and toward women in autoimmunity. Next-generation TCR variable beta chain (TCRBV) immunosequencing of 824 individuals was evaluated in a multiparametric analysis including HLA-A -B/MHC class I background, TCRBV usage, sex, age, ethnicity, and TCRBV selection/expansion dynamics. We found that HLA-associated shaping of TCRBV usage differed between the sexes. Furthermore, certain TCRBVs were selected and expanded in unison. Correlations between these TCRBV relationships and biochemical similarities in HLA-binding positions were different in CD8 T cells of patients with autoimmune diseases (multiple sclerosis and rheumatoid arthritis) compared with healthy controls. Within patients, men showed higher TCRBV relationship Spearman's rhos in relation to HLA-binding position similarities compared with women. In line with this, CD8 T cells of men with autoimmune diseases also showed higher degrees of TCRBV perturbation compared with women. Concerted selection and expansion of CD8 T cells in patients with autoimmune diseases, but especially in men, appears to be less dependent on high HLA-binding similarity than in CD4 T cells. These findings are consistent with studies attributing autoimmunity to processes of epitope spreading and expansion of low-avidity T cell clones and may have further implications for the interpretation of pathogenic mechanisms of infectious and autoimmune diseases with known HLA associations. Reanalysis of some HLA association studies, separating the data by sex, could be informative.

Dietary gluten triggers concomitant activation of CD4+ and CD8+ αβ T cells and γδ T cells in celiac disease

Celiac disease is an intestinal autoimmune disease driven by dietary gluten and gluten-specific CD4(+) T-cell responses. In celiac patients on a gluten-free diet, exposure to gluten induces the appearance of gluten-specific CD4(+) T cells with gut-homing potential in the peripheral blood. Here we show that gluten exposure also induces the appearance of activated, gut-homing CD8(+) αβ and γδ T cells in the peripheral blood. Single-cell T-cell receptor sequence analysis indicates that both of these cell populations have highly focused T-cell receptor repertoires, indicating that their induction is antigen-driven. These results reveal a previously unappreciated role of antigen in the induction of CD8(+) αβ and γδ T cells in celiac disease and demonstrate a coordinated response by all three of the major types of T cells. More broadly, these responses may parallel adaptive immune responses to viral pathogens and other systemic autoimmune diseases.

Mycobacterium bovis BCG scar status and HLA class II alleles influence purified protein derivative-specific T-cell receptor V beta expression in pulmonary tuberculosis patients from southern India

Purified protein derivative (PPD) RT23-recalled T-cell receptor (TCR) V beta expression was studied in the peripheral blood of 42 pulmonary tuberculosis patients and 44 healthy controls from southern India, a region where tuberculosis is endemic. Forty-eight-hour whole-blood cultures in the presence or absence of PPD-RT23 were set up, and at the end of the culture period total RNA was extracted and cDNA was synthesized. Expression of various TCR V beta families was assessed by using family-specific primers. PPD-specific expression (usage) of TCR V beta families 4, 6, 8 to 12, and 14 was found in more controls than patients. Among the responders (individuals who showed PPD-specific expression), endemic controls had significantly higher responses than the patients had for TCR V beta families 2, 3, 7, 13, and 17. The majority of the patients did not show usage of most of the TCR V beta families, and this was attributed to T-cell downregulation. A four-way nested classification analysis revealed that TCR V beta family 1, 5, 9, 12, and 13 usage in the context of HLA class II high-risk alleles (DRB1*1501, DRB1*08, and DQB1*0601) and Mycobacterium bovis BCG scar status were the determining factors in susceptibility and resistance to tuberculosis. The healthier status of controls was attributed to the wider usage of many TCR V beta families readily recalled by PPD, while the disease status of the patients was attributed to TCR V beta downregulation and the resultant T-cell (memory cell?) unresponsiveness. Host genetics (HLA status) and BCG vaccination (scar status) seem to play important roles in skewing the immune response in adult susceptibility to pulmonary tuberculosis through TCR V beta usage.

T-cell receptor repertoire in healthy Sardinian subjects

The T-cell receptor (TCR) Vbeta gene usage of CD4+ and CD8+ T-cell subpopulations was evaluated by flow cytometric analysis and by CDR3 spectratyping in healthy subjects belonging to Sardinian population, which is ethnically homogeneous and genetically distant from all other Italian and Caucasoid groups. As described in healthy Caucasian subjects, we found a nonrandom Vbeta gene usage and in some Vbeta families a significant skewed reactivity toward CD4+ T cells. Moreover, different subjects showed expansions in some Vbeta subfamilies, mainly in the CD8+ T cells. By CDR3 spectratyping analysis we found a significantly higher degree of skewness in the TCR Vbeta repertoire of CD8+ than in that of CD4+ T cells. The similarity found in the TCR Vbeta gene usage between the population examined and other Caucasoid groups suggest that the shape of the TCR repertoire is more influenced by rearrangement processes than ethnic background. However, genetic polymorphisms may condition the expression levels of some Vbetas, determining the variability of the TCR repertoire between different populations. Finally, the profound perturbations evidenced in the CD8+ T cell subpopulation could be related to a different response to the antigenic stimulation between CD8+ and CD4+ T lymphocytes.

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.

Possible extrathymic development of nonfunctional T cells in a patient with complete DiGeorge syndrome

Complete DiGeorge syndrome is characterized by the clinical triad of cardiac malformation, hypocalcemia, and T cell immunodeficiency due to congenital athymia. We describe an infant with complete DiGeorge syndrome who at presentation had no circulating T cells detectable by flow cytometry. The patient spontaneously developed circulating T cells but these cells did not proliferate in response to mitogens. The T cell receptor Vbeta repertoire was severely restricted. All T cells were host, not maternal, as assessed by fluorescent in situ hybridization evaluation of 22q11 hemizygosity. At autopsy, this patient had no grossly detectable thymus tissue and no microscopic evidence for thymopoiesis. These findings suggest that appearance of T cells in infants with complete DiGeorge syndrome may represent oligoclonal expansions of a small number of T cells that may have matured extrathymically and which do not respond in vitro to mitogen stimulation.

Specific Vβ T Cell Subsets Are Associated with Cat and Birch Pollen Allergy in Humans

Cognate interaction between TCRs and MHC class II molecules plays an important role in initiating the allergen-specific immune response. Therefore, we analyzed the TCR distribution of human PBLs of 56 atopic and nonatopic (NA) individuals, including 4 monozygotic twin pairs, from two extended and four nuclear families. The expression of 23 Vβ and 3 Vα elements was analyzed. The blood samples of symptomatic birch pollen-sensitized individuals that were taken ≤6 wk after the birch pollen season (n = 8) showed a significantly higher frequency of Vβ16.1+ and Vβ20.1+ T cells compared with the blood samples of birch pollen-sensitized individuals that were obtained out of allergen season (n = 10) or from NA individuals (p < 0.0005 and p < 0.0001, respectively). Allergen-specific lymphocyte proliferation was detected in the allergic individuals, and the distribution of Vβ16.1+ and Vβ20.1+ T cells returned to normal levels after the pollen season. The frequency of these Vβ-expressing T cells correlated with the levels of allergen-specific IgE Abs. In addition, cat-sensitized individuals (n = 8) showed a significantly higher frequency of Vβ17.1-expressing T cells than did NA individuals (p < 0.005). Our results indicate restricted TCR-Vβ gene usage in cat and birch pollen allergies; we suggest that both genetic and environmental factors contribute to TCR-Vβ gene expression and to the development of a specific T cell response.

Higher proportion of CD8+ T cells in the blood in healthy adults from Ethiopia and Bangladesh compared with Sweden

The phenotypic composition of peripheral blood lymphocytes in 45 healthy adults (15 each from Bangladesh, Ethiopia and Sweden) was analysed as an indicator of the influence of environment and/or ethnic background on the human immune response. The possible interference of technical factors was minimized by highly standardized handling of samples and by use of a similar simultaneous 3-colour flow cytometry analysis technique for all samples. The percentage of CD4+ cells was lower, and the percentage of CD8+ cells was higher, in Bangladeshi and Ethiopian subjects than in those from Sweden. A higher percentage of CD57+/CD8+ T cells was also found in these 2 groups than in Swedish subjects. The percentage of gamma delta T cells was higher in Bangladeshi subjects and a difference in T cell receptor V beta expression was also noted between Bangladeshi and Swedish subjects. The data suggest that environmental or genetic factors are important bias factors to be considered in immunophenotyping studies. Possibly differences in the pattern or level of microbial challenge, as well as nutritional factors, may lead to different adaptive changes in the immune response. The potential influence of such immune adaptation on the response to vaccination or pharmaceutical therapy may be important in the development of new strategies of medical intervention in different geographical regions or ethnic groups.

Normalization of the peripheral blood T cell receptor V beta repertoire after cultured postnatal human thymic transplantation in DiGeorge syndrome

Complete DiGeorge syndrome is an immunodeficiency disease characterized by thymic aplasia and the absence of functioning peripheral T cells. A patient with this syndrome was transplanted with cultured postnatal human thymic tissue. Within 5 weeks of transplantation, flow cytometry, T cell receptor V beta sequence analysis, and cell function studies showed the presence of oligoclonal populations of nonfunctional clonally expanded peripheral T cells that were derived from pretransplantation T cells present in the skin. However, at 3 months posttransplantation, a biopsy of the transplanted thymus showed normal intrathymic T cell maturation of host T cells with normal TCR V beta expression on thymocytes. By 9 months postransplantation, peripheral T cell function was restored and the TCR V beta repertoire became polyclonal, coincident with the appearance of normal T cell function. These data suggest that the transplanted thymus was responsible for the establishment of a new T cell repertoire via thymopoiesis in the chimeric thymic graft.

Molecular analysis of highly enriched populations of T-cell-depleted monocytes

CD4+ T lymphocytes and monocytes/macrophages are important components of the immune system. Blood monocytes are usually targeted for studies of the human macrophage lineage cells because of their accessibility through blood sampling. Most separation techniques currently available to obtain human monocytes either require large volumes of blood or do not yield a monocyte fraction sufficiently depleted of other cell types. We have developed a simple strategy to isolate a highly enriched population of monocytes from small volumes (< 6 ml) of peripheral blood by using an anti-CD14 monoclonal antibody and magnetic microspheres. Yields of monocytes ranged from 75 to 80% of CD14+ cells in peripheral blood. CD4+ T cells were subsequently selected from the monocyte-depleted peripheral blood by using an anti-CD4 monoclonal antibody and immunomagnetic beads. The effectiveness of immunomagnetic selection to yield a monocyte population highly depleted of T cells was analyzed by using a sensitive molecular strategy based on PCR amplification and detection of T-cell receptor (TCR) gene rearrangements. The relative frequency of rearranged TCRs within the monocyte population was compared with the frequency of rearranged TCRs within the CD4+ T-cell fraction from the same individual. Molecular analysis indicated that a viable monocyte population which contains fewer than 2% residual T lymphocytes can be consistently selected from small aliquots of blood.

Large granular lymphocyte expansions in patients with Felty's syndrome: analysis using anti-T cell receptor V beta-specific monoclonal antibodies

Felty's syndrome (FS), the association of rheumatoid arthritis (RA) and idiopathic neutropenia, remains an unexplained phenomenon. HLA-DR4 is found in over 90% of cases. Patients with FS may have a T cell lymphocytosis of CD3+CD8+CD57+ large granular lymphocytes (LGL syndrome). In this study of 47 patients with FS, 19% had clear evidence for LGL expansions, while in total 42% had variable evidence for the LGL syndrome using currently available techniques. Of these T cell expansions, 76% were clonal, as demonstrated by Southern blotting and analysis with T cell receptor (TCR) beta chain constant region probes. This technique may fail to detect clonal populations in some patients. Cytofluorographic analysis using antibodies specific for TCR V beta chains identified patients with clonal LGL expansions with results comparable to those obtained with Southern blotting. No evidence for shared V beta usage among expansions from different patients was seen. The role of LGL in RA and FS is currently unclear, but this technique offers a practical and accessible means of identifying patients with LGL expansions, as a starting point for further investigation.

Influence of HLA class I and class II antigens on the peripheral T-cell receptor repertoire

Using TCR-specific mAbs, we analyzed the TCR distribution in the CD4 and CD8 compartments of peripheral blood T cells from members of six families, including two which were informative for an HLA-B/DR crossover. TCR distribution in the CD4 compartment is influenced by MHC class II antigens as it was similar in the child carrying the HLA-B/DR recombination and in the HLA-DR-identical sibling. There was also a relatively small degree of difference between TCR distribution in the CD8 compartment of a child with an HLA-B/DR crossover and his HLA class-I-identical sibling. Analysis of TCR V beta gene usage in the CD4 compartment of unrelated individuals sharing an HLA-DR allele showed an increased usage of V beta 8a and V beta 12a in DR4-positive subjects. These data suggest that studies of TCR V beta gene usage in individuals with HLA-associated autoimmune diseases may provide further information about MHC-dependent biases in the T-cell repertoire.

Population study of T cell receptor V beta gene usage in peripheral blood lymphocytes: differences in ethnic groups

The T cell receptor (TCR) V beta repertoire in peripheral blood lymphocytes (PBL) of a large number of healthy individuals was analysed by quantifying V beta-specific mRNA using the method of anchored multiprimer DNA amplification and a reverse dot blot assay. Among 16 V beta gene families examined, particular V beta genes were noted to be unequally expressed in the PBL of 70 healthy donors. The frequently used genes belong to the V beta 4, 5, 6, 8 and 13 (12) families, while V beta 1, 9 and 15 were the least frequently used gene families. This bias in gene usage was observed in all individuals. Marked deviation from the mean percentage usage was noted for some V beta genes in individuals when their PBL were examined serially, but the common pattern of biased usage was not grossly distorted. When the TCR repertoire of different ethnic groups was examined, a lower mean frequency of V beta 3.2 was seen in the repertoire of 19 Caucasians compared with 25 age-matched Samoans (P < 0.003). Conversely, the expression of V beta 5.1 and V beta 5.3 was higher in Caucasians than in 51 age-matched Polynesians (Maoris and Samoans, P < 0.003). Considering the 20% co-efficient of variation in the estimate of V beta gene usage, our data from 70 unrelated individuals suggest that in PBL, individual variations in the TCR repertoire were superimposed upon a common biased usage of V beta genes in the general population.

The T-cell response to myelin basic protein in familial multiple sclerosis: diversity of fine specificity, restricting elements, and T-cell receptor usage

Indirect evidence suggests that an autoimmune response to myelin basic protein (MBP) may be involved in the pathogenesis of multiple sclerosis (MS). In MS, several reports have suggested that restricted T-cell populations respond to MPB, as in inbred rodents with the MS disease model experimental allergic encephalomyelitis. In experimental allergic encephalomyelitis, the T-cell repertoire to MBP varies between strains, and in MS it is likely that the response to MBP is also best defined under conditions where genetic differences between subjects are controlled. In this report, the fine specificity of the T-cell response to MBP was assessed in three families, each with multiple individuals affected with MS. We found that (1) comparable frequencies of MBP-reactive T-cell lines were obtained from peripheral blood of MS patients and their healthy siblings. Human leukocyte antigen (HLA) identical sibling pairs discordant for MS had similar frequencies of MBP-reactive T-cell lines. (2) A broad spectrum of MBP epitopes was recognized by T-cell lines from all individuals studied. Within a family, the fine specificity of MBP recognition showed little or no overlap between individuals, even between HLA identical siblings. (3) Recognition of MBP epitopes occurred in the context of different HLA class II alleles. At least four DR alleles each served as restricting elements for recognition of P82-101 or the carboxy terminal region of MBP, two regions thought to be important in the human T-cell response to the molecule. No relationship between the use of a particular DR allele and a response to a particular region of MBP could be established.(ABSTRACT TRUNCATED AT 250 WORDS)

Lack of selective V beta deletion in peripheral CD4+ T cells of human immunodeficiency virus-infected infants

To investigate the possibility of super-antigen-mediated deletions of T cells expressing particular T cell receptor V beta (TcR V beta) gene segments during human immunodeficiency virus (HIV) infection, TcR V beta usage in CD4+ and CD8+ subsets was analyzed in a cohort of infants maternally infected by HIV and in a group of healthy neonates. We used a semi-quantitative anchored polymerase chain reaction technique together with cytofluorographic analysis with anti-V beta monoclonal antibodies. The representation of the 24 V beta families in CD4+ and CD8+ T cells from normal neonates was very similar to that in adults. Preferential expression of V beta 2 in the CD4+ subset was observed in both the neonates and in healthy adults. The representation of the 24 V beta families in peripheral CD4+ T cells from the HIV-infected infants showed no selective V beta deletion, even when the CD4+ subset was globally depleted. Moreover, the main characteristics of the control group (predominance of certain V beta families and V beta 2 skewing towards the CD4+ subset) were also present in all the HIV-infected infants.

The human T-cell receptor beta-chain repertoire: longitudinal fluctuations and assessment in MHC matched populations

The influence of the environment and of the major histocompatibility complex (MHC) in shaping the human T-cell receptor beta-chain variable region (TCRBV) repertoire has not been systematically studied. Here, expression of TCRBV gene families was estimated by a sensitive polymerase chain reaction (PCR)-based method. Serial studies of peripheral blood, performed at 2-week intervals over a 3-month period, revealed that fluctuation in the expression of many TCRBV genes occurred in healthy individuals and in the absence of clinically evident infections. Fluctuation of TCRBV4, TCRBV5.2, TCRBV9, and TCRBV13.1 genes were present in all subjects. Additional TCRBV genes fluctuated in some but not in other individuals. Comparison of the TCRBV repertoire between these unrelated individuals indicated differences in the mean expression of TCRBV5.1, TCRBV9, TCRBV11, TCRBV15, TCRBV17, and TCRBV20 genes. For any TCRBV gene, intersubject differences were generally of a magnitude of twofold or less. Larger differences characterized the TCRBV repertoire of CD4 compared to CD8 cells. Some differences, for example over-representation of TCRBV2 and TCRBV5.1 on CD4, and TCRBV10, TCRBV14, and TCRBV16 on CD8 cells, were present in most subjects. Individuals homozygous for DR2- or DR3-bearing extended MHC haplotypes displayed similar individual variability of TCRBV expression. These data indicate that the circulating TCRBV repertoire in humans is both dynamic and diverse. Both environment and MHC effects contribute to the diversity of TCRBV expression.

Changes in the cytotoxic T-cell repertoire of HIV-1-infected individuals: relationship to disease progression

The repertoire of antigen-specific receptors expressed on T lymphocytes is shaped by fixed genetic and variable environmental selective pressures. Recent technological advances have enabled the analysis of T-cell receptor (TCR) expression in the context of selective pressures arising through normal immune system development and also through pathological features of disease. The pathological features of acquired immune deficiency syndrome (AIDS) are reflected by selective depletion of particular T lymphocyte subsets and expansion of others. An important question concerning the immunopathogenesis of AIDS is whether or not the perturbation of the CD4+ and CD8+ T-cell subsets following infection with human immunodeficiency virus (HIV) is selective based on TCR variable (V) region gene expression. To address this question, we have functionally analyzed TCR V gene expression on CD8+ cytotoxic T lymphocytes from HIV-1-infected individuals. This was done using monoclonal antibodies against individual TCR V regions to trigger redirected cytolysis in 51Cr release assays. The percent specific lysis induced by each antibody functionally measures the representation of the TCR V region gene product it is specific for. Relative to non-HIV-infected controls and asymptomatic HIV-infected individuals with only moderate CD4 lymphocyte depletion, HIV-infected individuals with low CD4 lymphocyte counts exhibited skewed patterns of TCR V region representation. Therefore, the perturbation within the CD8+ cytotoxic T lymphocyte repertoire in HIV infection appears to be selective based on TCR V region usage, increasingly so as disease progresses. The TCR V genes affected varied between different HIV-infected individuals and skewing detected in functional assays was not always apparent by flow cytometric analysis. These results suggest that HIV infection causes generalized effects on the T-cell repertoire, which are reflected in the relative TCR V gene representation of the CD8+ cytotoxic T lymphocyte population in peripheral blood.