T cell vaccination: clinical application in autoimmune diseases

 T cell responses to myelin basic protein (MBP) are implicated to play an important role in the pathogenesis of multiple sclerosis (MS). These MBP autoreactive T cells are found to undergo in vivo activation and clonal expansion in patients with MS. They accumulate in the brain compartment and may reside in the brain lesions of patients with MS. As MBP-reactive T cells potentially hold a central position in initiation and perpetuation of the brain inflammation, specific immune therapies designed to deplete them may improve the clinical course of the disease. We review here the recent application of T cell vaccination in patients with MS to deplete circulating MBP-reactive T cells. The results of our phase I clinical trial indicate that T cell vaccination with inactivated MBP autoreactive T cells induces specific regulatory T cell network of the host immune system to deplete circulating MBP-reactive T cells in a clonotype-specific fashion. The immunity induced by T cell vaccination is clonotype specific and long-lasting. Our longitudinal clinical evaluation further suggests a moderately lower rate of clinical exacerbation, disability score, and brain lesions (measured by magnetic resonance imaging) in vaccinated patients than in matched controls. Our study should encourage further investigation on the treatment efficacy of T cell vaccination and further improvement for its clinical administration in other human autoimmune diseases. This review discusses the immune regulation and therapeutic administration of T cell vaccination in human autoimmune diseases, exemplified by our recent T cell vaccination trial in MS. Received: 14 March 1996 / Accepted: 18 July 1996     

The role of hepatitis C virus specific CD4+ T lymphocytes in acute and chronic hepatitis C

 Since the discovery of hepatitis C virus it has become clear that chronic hepatitis C is a major health problem throughout the world. Because antiviral agents are of limited value in the treatment of chronic hepatitis C, research has focused on the antiviral immune response for the development of both a protective vaccine and effective immunotherapies for established chronic infection. Antiviral antibodies are present in almost all patients with chronic hepatitis C but do not seem to be virus neutralizing, probably due to the high mutational rate of viral envelope proteins. Studies on the antiviral T cell response have revealed the presence of virus-specific CD4⁺ helper and CD8⁺ cytotoxic T cells in a substantial proportion of patients with chronic hepatitis C. Recent studies describe an association between strong CD4⁺ T helper cell activity to certain hepatitis C virus antigens and a self-limited course of acute hepatitis C and possibly also a sustained response to treatment with interferon-α. Therapeutic manipulation of the virus-specific T cell response may thus develop into a new approach for prevention and treatment of hepatitis C virus infection. Received: 12 March 1996 / Accepted: 18 June 1996     

Antibacterial vaccines: impact of antigen handling and immune response

 The emerging awareness that diseases caused by bacterial pathogens cannot be vanquished by chemotherapy alone has recalled interest in the generation of novel vaccines. Vaccines have proven their efficacy for the bacterial pathogens that are controlled by antibodies. In contrast, satisfactory vaccines are not available for intracellular bacteria that are under the control of T lymphocytes. This review describes the T cell populations that must be activated by successful vaccines against intracellular bacteria and discusses parameters that need to be fulfilled by protective T cell antigens. These parameters include: (a) the intracellular localization of the pathogen with major effect on antigen presentation and stimulation of distinct T cell subsets and (b) the antigen display which markedly influences kinetics of T cell activation. Using tuberculosis as an example, the advantages and disadvantages of second-generation vaccine candidates are discussed. Received: 21 October 1996 / Accepted: 18 November 1996     

Subpopulations of T lymphocytes in the peripheral blood and lymph nodes of Indian kala-azar patients

Distribution of T cells in the peripheral blood and lymph nodes of Indian kala-azar (KA) patients was studied by using appropriate phenotypic markers for CD2⁺, CD4⁺ and CD8⁺ cells. Significant reduction in the CD2⁺, CD4⁺ cell numbers as well as CD4⁺/CD8⁺ cell ratio was noted in the peripheral blood of active KA cases. Such alteration in the T cell population appeared to be a manifestation of the disease process as it showed a tendency to return close to normalcy several months after successful chemotherapy. Histopathological studies of KA patients with lymphadenopathy demonstrated gradual destruction of lymph node follicular architecture which correlated well with the severity and duration of illness. Massive infiltration of CD2⁺ cells in the cortical region of lymph node was evident. The observed preponderance of CD4⁺ cells over CD8⁺ ones in these infiltrates was in sharp contrast to the distribution pattern of these cells in the periphery. Significance of these findings is discussed in relation to the current concepts on the immunology of leishmaniasis and related diseases. Received: 20 May 1996     

同种特异T细胞疫苗诱导移植物存活期延长的研究——Ⅱ.抗独特型T细胞免疫反应

同种特异T细胞疫苗(TCV)免疫诱导出同种免疫反应低下,同种移植物存活时间显著延长,推测其作用机制可能是同种特异TCV免疫诱导机体抗同种特异TCV(独特型)T细胞的上调.实验证实了“抗TCV-T细胞”的存在.以同种特异TCV免疫动物可诱导出对TCV特异的细胞增殖反应.TCV免疫小鼠淋巴细胞能特异杀伤TCV细胞.将TCV免疫小鼠脾细胞作为调节细胞,观察到它能显著地抑制同种MLR,表明它是一“抑制性T细胞”.这些结果提示,同种特异TCV免疫可诱导机体免疫网络中独特型-抗独特型的上调,产生了同种反应T细胞的独特型T细胞,从而保护同种移植物免受同种反应性T细胞的攻击使同种移植物存活时间显著延长.     

Antigen presenting cell-derived co-stimulatory signals can selectively regulate IL-2 and IL-4 production from a Th0 cell hybridoma

T_h0 cells are a subpopulatlon of T_h cells that produce bothIL-2 and IL-4. In order to study the selective regulation oflymphokines in T_h0 cells, a T_h0 cell hybridoma, GA15, was generatedby fusing a T_h2 clone with the thymoma BW5147. The pattern oflymphokines secreted by GA15 was found to depend on the antigenpresenting cells (APC) used for stimulation. When GA15 was stimulatedwith antigen and splenocytes, both IL-2 and IL-4 were produced.However, when the B cell hybridoma LB was used as APC, onlyIL-2 was detected. Although LB cells could not stimulate IL-4production, they were more potent than were spleen cells atinducing IL-2 production, demonstrating that the differencebetween the two APC populations was qualitative rather thanquantitative. Similar results were seen upon stimulation withconcanavalin A or anti-CD3 mAb. Regulation of interferon- productionparalleled regulation of IL-4 production. The failure of LBcells to stimulate IL-4 production was not due to inhibitionor consumption of IL-4 and the activity could not be restoredby adding IL-1, spleen cell supernatants or spleen cells lackingthe appropriate MHC molecule. Finally, the parent T_h2 cloneused in the fusion showed a similar inability to produce IL-4in response to LB cells. These data indicate that APC-derivedco-stimulatory signals can selectively affect IL-2 and IL-4production in a T_h0 cell hybridoma. Therefore, the choice ofAPC may lead to selective stimulation of particular lymphokinesby acting on T_h0 cells.     

Effector memory T cell subset CD45RA−CCR7−CD27−CD28− EM3 increases in direct proportion to the disease severity of COVID-19

COVID-19, which emerged in December 2019 and continues to wreak havoc, has led to the death of many people around the world. In this study, we aimed to uncover the variables underlying the exacerbation of the disease by considering the changes in T cell subsets in adults and juveniles with different disease severity of COVID-19. Peripheral blood samples of 193 patients (128 adults and 65 juveniles) diagnosed with COVID-19 were evaluated in a flow cytometer, and a broad T cell profile was revealed by examining T cell subsets in terms of exhaustion and senescence. We found remarkable differences in the effector memory (EM; CD45RA⁻CCR7⁻) cell subsets of severe pneumonia cases. The frequencies of EM₂ CD4⁺ T, EM₃ CD4⁺ T, EM₃ CD8⁺ T, EM₂ DN T and EM₃ DN T cells were found to increase in severe pneumonia cases. Consistently, these cells were found in juveniles and uncomplicated adults in similar or lower proportions to healthy controls. The findings of our study provide a view of the T cell profile that may underlie differences in the course of COVID-19 cases in juveniles and adults and may provide new insights into the development of effective treatment strategies.     

Separately expressed T cell receptor α and β chain transgenes exert opposite effects on T cell differentiation and neoplastic transformation

Two aspects of T cell differentiation in T cell receptor (TCR)-transgenic mice, the generation of an unusual population of CD4^?CD8^?TCR⁺ thymocytes and the absence of γδ cells, have been the focus of extensive investigation. To examine the basis for these phenomena, we investigated the effects of separate expression of a transgenic TCR α chain and a transgenic TCR β chain on thymocyte differentiation. Our data indicate that expression of a transgenic TCR α chain causes thymocytes to differentiate into a CD4^?CD8^?TCR⁺ lineage at an early developmental stage, depleting the number of thymocytes that differentiate into the αβ lineage. Surprisingly, expression of the TCR α chain transgene is also associated with the development of T cell lymphosarcoma. In contrast, expression of the transgenic TCR β chain causes immature T cells to accelerate differentiation into the αβ lineage and thus inhibits the generation of γδ cells. Our observations provide a model for understanding T cell differentiation in TCR-transgenic mice.     

儿童T细胞活化时细胞内钙离子的变化

本文用钙指示剂Ｆｌｕｏ－３标记正常儿童外周血单个核细胞，经流式细胞仪分析了几种激活剂对Ｔ细胞内钙离子浓度的影响。结果表明：（１）静止期Ｔ细胞内钙离子浓度为１６２±８７ｎＭ，抗ＣＤ３单克隆抗体交联ＧＡＭＩｇ刺激后，Ｔ细胞内钙离子浓度上升；（２）用抗ＣＤ３单克隆抗体和ＩＬ－２或ＰＭＡ和ｉｏｎｏｍｙｃｉｎ作用Ｔ细胞，细胞内钙离子浓度上升，但其浓度低于用抗ＣＤ３单克隆抗体交联ＧＡＭＩｇ刺激时的浓度；（３）去除抗ＣＤ３单克隆抗体和ＩＬ－２或ＰＭＡ和ｉｏｎｏｍｙｃｉｎ对Ｔ细胞的作用，培养后细胞内钙离子浓度又恢复到静止状态，再加入抗ＣＤ３单克隆抗体交联ＧＡＭＩｇ刺激发现细胞内钙离子显著地升高；（４）钙离子阻断测定提示早期钙离子升高是Ｔ细胞内钙离子池释放的，而细胞外钙离子的流入对于维持钙离子持续上升是必要的。     

Origin of CD8^＋ Effector and Memory T Cell Subsets

It is well accepted that CD8＋ T cells play a pivotal role in providing protection against infection with intracellular pathogens and some tumors. In many cases protective immunity is maintained for long periods of time （immunological memory）. Over the past years, it has become evident that in order to fulfill these multiple tasks, distinct subsets of effector and memory T cells have to be generated. Until today, however, little is known about the underlying mechanisms of subset differentiation and the timing of lineage fate decisions. In this context, it is of special importance to determine at which level of clonal expansion functional and phenotypical heterogeneity is achieved. Different models for T cell subset diversification have been proposed; these differ mainly in the time point during priming and clonal expansion （prior, during, or beyond the first cell division） when differentiation programs are induced. Recently developed single-cell adoptive transfer technology has allowed us to demonstrate that individual precursor cell still bears the full plasticity to develop into a plethora different T cell subsets. This observation targets the shaping of T cell subset differentiation towards factors that are still operative beyond the first cell division. These findings have important implications for vaccine development, as the modulation of differentiation patterns towards distinct subsets could become a powerful strategy to enhance the efficacy and quality of vaccines. Cellular ＆ Molecular Immunology.     

Clonal growth of carp (Cyprinus carpio) T cells in vitro

Carp kidney leukocytes co-cultured with a supporting cell layer resulted in the rapid proliferation of various types of leukocytes including immature leukocytes. Expressions of marker genes for multiple blood cell lineages were observed in the primary culture. However, after several passages, the proliferating cells expressed only T cell and macrophage marker genes.Further RT-PCR analysis revealed that the proliferating cells expressed TCR constant regions (Cα, Cβ, Cγ, Cδ), CD3γ/δ and CD4 (CD4L-1), but did not express CD8α and CD8β. Additionally, in situ hybridization analysis showed that the majority of proliferating cells expressed Cα, Cβ, Cγ, Cδ and CD4. Moreover, 5′-RACE sequences of TCR variable regions (Vα, Vβ, Vγ, Vδ) revealed that the proliferating cells contained a polyclonal T cell repertoire, and most of the Vα and Vβ sequences were functional, but the Vγ and Vδ sequences were non-functional with frame shifts and stop codons. Taken together, these results indicate that the proliferating cells after serial passages predominantly contained CD4+ CD8− αβT cells that simultaneously co-expressed non-functional γδTCR. To obtain CD4+ αβT cell (helper T cell) clones, single cells were picked up from the bulk culture, seeded into each well of 96-well plates and cultured in the presence of supporting cells and conditioned media. T cell colonies formed from single cells after 2-3 weeks. These colony cells expressed Cα, Cβ, Cδ and CD4, and weakly expressed Cγ, but did not express CD8α, CD8β and CD4L-2. Taken together, these results indicate that these clonal T cells resemble a subpopulation of mammalian CD4+ helper T cells.     

Induction of T cell responses by chimeric bacterial proteins expressing several copies of a viral T cell epitope

A viral T cell epitope was genetically inserted within the periplasmic MalE protein of Escherichia coli in two different permissive insertion sites and resulting hybrid proteins were used to study the in vitro and in vivo immunogenicity of the foreign T cell epitope. Purified hybrid MalE proteins containing the T cell epitope 120-132 (PreS:T) from PreS2 region of hepatitis B virus HBsAg inserted alone or with its adjacent B cell epitope (132-145) were able to induce strong peptide-specific T cell responses in mice. In vitro stimulation of primed lymph node cells or specific T cell hybridomas by the hybrid proteins required processing of the inserted T cell epitope and was inhibited by antigen-presenting cells fixation. The inserted T cell epitope was presented in vitro, in association with appropriate major histocompatibility complex molecules, as efficiently as free synthetic peptide. The in vitro immunogenicity of MalE hybrid proteins was increased by inserting four tandemly repeated copies of PreS:T, either at site 133 or 303. These results were confirmed in vivo by comparing the proliferative responses of lymph node cells from DBA/1 mice primed with MalE hybrid proteins containing one or four copies of PreS:T. Thus, the use of MalE hybrid proteins expressing multiple copies of a given foreign T cell epitope allows the induction of peptide-specific T cell response with a lower dose of priming antigen.     

Peripheral T cell and natural killer (NK) T cell lymphomas: a clinicopathological study from a single Australian centre

McKelvie P A, Thompson P A & Tam C S
(2012) Histopathology  61, 212–233 Peripheral T cell and natural killer (NK) T cell lymphomas: a clinicopathological study from a single Australian centre Aims: Using pathological and clinical review, to identify all cases diagnosed as peripheral T cell and natural killer (NK) T cell lymphoma over 10 years from one metropolitan Australian hospital. Methods and results: Subtyping was performed using World Health Organization (WHO) 2008 criteria and a comprehensive immunohistochemical panel. Clinical data including follow‐up were obtained. There were 47 cases, including 11 peripheral T cell lymphomas, not otherwise specified (NOS), nine extranodal NK T cell lymphomas, nasal type (eight nasal), eight primary cutaneous anaplastic large cell lymphomas, seven angioimmunoblastic T cell lymphomas, three anaplastic lymphoma kinase (ALK)‐positive anaplastic large cell lymphomas, four ALK‐negative anaplastic large cell lymphomas, three enteropathic T cell lymphomas and two subcutaneous panniculitis‐like T cell lymphomas. Follow‐up of 46 of 47 cases (median time 45 months) revealed that 50% (23 of 46) of patients died. Five‐year survival rates were: peripheral T cell lymphoma, NOS 39%; angioimmunoblastic T cell, 43%; nasal NK T 67%; ALK‐negative anaplastic large cell lymphoma 67% (at 2 years); ALK⁺ anaplastic large cell lymphoma 33%; subcutaneous panniculitis‐like T cell lymphomas 100%; primary cutaneous anaplastic large cell lymphoma 86%; and enteropathic T cell lymphoma 33% (at 1 year). One patient with Lennert lymphoma suffered four late cutaneous relapses. Conclusions: This first Australian clinicopathological series of peripheral T cell and NK T cell lymphoma shows epidemiological and survival data similar to those for Europe and North America.     

Determination of cell expansion and surface molecule expression on anti‐CD3/28 expanded CD4+ T cells

CD4⁺ T cell immunotherapy has potential for treatment in HIV‐infected patients. A large number of expanded CD4⁺ T cells and confirmation of functional‐related phenotypes are required for ensuring the successful outcomes of treatment. Freshly isolated CD4⁺ T cells from healthy donors were activated with anti‐CD3/28‐coated magnetic beads at different bead‐to‐cell ratios and cultured in the absence and presence of IL‐2 supplementation for 3 weeks. Fold expansion, cell viability, growth kinetic and lymphocyte subset identities were determined. Data demonstrated that a 1:1 bead‐to‐cell ratio rendered the highest expansion of 1044‐fold with 88% viability and 99.5% purity followed by the 2:1 and 0.5:1 ratios. No significant difference in proliferation and phenotypes was found between non–IL‐2 and IL‐2 supplementation groups. Several specific surface molecule expressions of the expanded cells including chemokine receptors, adhesion molecules, co‐stimulatory molecules, activation molecules, maturation markers, cytokine receptors and other molecules were altered when compared to the unexpanded cells. This optimized expansion protocol using the 1:1 bead‐to‐cell ratio of anti‐CD3/28‐coated magnetic beads and culture condition without IL‐2 supplementation provided the satisfactory yield with good reproducibility. Specific surface molecule expressions of the expanded cells presented potential roles in proliferation, differentiation, homeostasis, apoptosis and organ homing.     

Peripheral T cell lymphomas with follicular T helper phenotype: a new basket or a distinct entity? Revising Karl Lennert’s personal archive

Agostinelli C, Hartmann S, Klapper W, Korkolopoulou P, Righi S, Marafioti T, Piccaluga P P, Patsouris E, Hansmann M‐L, Lennert K & Pileri S A
(2011) Histopathology 59 , 679–691 Peripheral T cell lymphomas with follicular T helper phenotype: a new basket or a distinct entity? Revising Karl Lennert’s personal archive Aims: To revise 25 cases selected from Karl Lennert’s personal archive (21) and Bologna and Frankfurt Registries (four) because of cytological similarities. Methods and results: All cases were provided with paraffin blocks and studied by immunohistochemistry and molecular techniques. While phenotyping was very informative, among molecular studies only EBER in situ‐hybridization (ISH) was successful. Twenty‐two cases were concluded as peripheral T cell lymphomas (PTCL). Of these, six were reclassified as angioimmunoblastic T cell lymphoma (AITL), 13 as PTCL, not otherwise specified (NOS), including four follicular variants and one tumour with T‐zone pattern, and three as borderline tumours between AITL and PTCL/NOS. All these cases consisted homogeneously of small/medium‐sized elements with mild nuclear atypia and an evident rim of clear/pale cytoplasm. On immunohistochemistry, they regularly expressed three to six follicular helper T cell (FTH)‐associated markers. EBER–ISH revealed scattered EBV‐infected B cells in all tumours except those with ‘follicular’ growth pattern. The content of follicular dendritic cells and high‐endothelial venules varied significantly depending on the histotype. Conclusions: This study shows that: (i) historical material can be still employed usefully, and (ii) the FTH‐phenotype corresponds to a broad spectrum of PTCLs that might form a new category to be validated in future molecular and clinicopathological analyses.     

调节性T细胞及其分泌的细胞因子在再生障碍性贫血中的意义

目的:检测再障患者外周血中T细胞亚群比例及Treg细胞相关的细胞因子分泌水平,探讨其在再障发病中作用。方法:依据临床诊断标准,收集初发再障组、再障造血恢复组、正常对照组的外周血标本,流式细胞学方法检测各组CD4+、CD8+、NK、NKT、Treg细胞的比例,免疫磁珠法分离各组外周血中Treg细胞,并给予刺激培养,24、48小时后收集上清液,酶联免疫吸附试验(ELISA)检测Treg细胞分泌的细胞因子IL-10、IL-35、TGF-β的表达水平。结果:初发再障组的CD4+,Treg比例与正常对照组和再障造血恢复组相比显著低下;CD8+T细胞比例在再障患者中明显升高,其结果有统计学差异(P<0.05);NK、NKT的细胞与正常对照组比较无明显变化(P>0.05)。分离培养三组人群Treg细胞,ELISA检测结果显示:初发再障患者的IL-10、IL-35、TGF-β表达水平和正常对照组比较明显降低(P<0.05)。结论:T细胞免疫异常是再障发病机制的重要环节,Treg细胞在再障患者恢复造血过程中可能起着正向调控的作用。     

Allergic patients have more numerous and prolonged respiratory infections than nonallergic subjects

BACKGROUND: Allergic disorders are characterized by type 2 helper T cell (Th2)-polarization, thus physiological type 1 helper T cell (Th1)-dependent mechanisms involved in fighting respiratory infections (RI) may be defective. It has previously been reported that allergic children have more numerous and severe RI than nonallergic ones. OBJECTIVE: The aim of the study was to evaluate the number and duration of RI in adult allergic and nonallergic subjects. METHODS: Six hundred and twenty-four subjects were studied; 202 of them were allergic (i.e. suffering from allergic rhinitis). The number of RI as well as the duration of the disease were recorded for 2 years. RESULTS: Allergic subjects showed a significantly higher rate of RI episodes [adjusted incidence rate ratio (IRR) = 2.16, 95% confidence interval (CI) 1.94-2.41, P < 0.001] than subjects without allergy. The number of mild RI episodes was slightly higher in allergic subjects (IRR = 1.68, 95% CI 1.50-1.89, P < 0.001), while the number of severe episodes was markedly higher (IRR = 15.71, 95% CI 10.35-23.84, P < 0.001) when compared with nonallergic subjects. Moreover, allergic patients showed a longer total duration of RI than nonallergic subjects, with a mean difference of 17.4 days (95% CI 15.5-19.4, P < 0.001). CONCLUSIONS: This study provides evidence that adult allergic patients have more numerous and prolonged RI than nonallergic subjects.     

肺结核患者外周血CD4~+和CD8~+记忆性T细胞亚群、IL-17、IL-27表达的初步探讨

目的:探讨肺结核患者外周血CD4+和CD8+记忆性T细胞亚群及白细胞介素17(Interleukin-17,IL-17),IL-27的表达。方法:采用流式细胞术检测肺结核患者组外周血CD4+和CD8+记忆性T细胞,患者组按治疗史分为初治组,复治组;按痰涂片抗酸染色分为痰涂阳性组,痰涂阴性组。初治组8例为凡既往未用过抗结核药物治疗或用药时间少于一个月的新发病例;复治组22例为凡既往应用抗结核药物一个月以上的新发病例、复发病例、初治治疗失败病例等;痰涂阳组9例为痰涂片抗酸染色阳性;痰涂阴组21例为痰涂片抗酸染色阴性。ELISA法检测IL-17,IL-27。结果:①与健康对照组比较:患者组CD4+效应型记忆性T细胞均显著增高(P<0.05),初治组与涂阴组CD8+效应型记忆性T细胞均显著降低(P<0.05),复治组IL-17显著降低(P<0.05),而IL-27显著增高(P<0.05)。②与初治组比较:复治组CD4+中央型记忆性T细胞显著降低(P<0.05),而CD8+效应型记忆性T细胞显著增高(P<0.05),IL-17显著降低(P<0.05),IL-27显著增高(P<0.05)。③与涂阴组比较:涂阳组CD4+中央型记忆性T细胞显著降低(P<0.05),CD8+效应型记忆性T细胞显著增高(P<0.05),CD8+中央型记忆性T细胞显著降低(P<0.05)。④Spearman相关性分析显示:IL-17与IL-27呈正相关(P<0.05),记忆性T细胞亚群与IL-17,IL-27水平无显著相关性(P>0.05)。结论:肺结核患者外周血CD4+效应型记忆性T细胞的表达可望作为TB初步诊断的观察指标,CD4+中央型记忆性T细胞和CD8+效应型记忆性T细胞的表达均可望作为TB患者的临床分组依据,TB外周血IL-17、IL-27水平可望用于判断TB的炎症程度。     

Immune activation in the context of HIV infection

Our objective was to study whether CD4⁺ or CD8⁺ T cells expressing particular T cell receptors (TCR) would accumulate in the lungs of patients with allergic asthma following allergen exposure. We thus analysed the TCR Vα and Vβ gene usage of CD4⁺ and CD8⁺lung and peripheral blood lymphocytes (PBL) of eight patients with allergic asthma before and 4 days after inhalation challenge with the relevant allergen. Lung cells obtained by bronchoalveolar lavage (BAL) and paired PBL samples were analysed by flow cytometry using a panel of anti-TCR V-specific monoclonal antibodies that encompass ≈ 50% of the T cell repertoire. Lung-limited T cell expansions were recorded in both the CD4⁺and the CD8⁺subsets. In BAL CD8⁺, out of a total of 126 analyses, the number of T cell expansions increased from two to 11 after challenge, some of them dramatic. In BAL CD4⁺the frequency of expansions was moderately increased already before challenge, but remained unchanged. A few expansions that tended to persist were noted in PBL CD8⁺. When analysing the overall change in TCR V gene usage the largest changes were also recorded in the BAL CD8⁺subset. Specific interactions between T cells and antigens may lead to an increased frequency of T cells using selected TCR V gene segments. In this study we demonstrate that following allergen bronchoprovocation in allergic asthmatic subjects, T cell expansions preferentially emerge in the lung CD8⁺T cell subset.