Decreased Peripheral Blood Natural Killer Cell Count in Untreated Juvenile Dermatomyositis Is Associated with Muscle Weakness.

Juvenile Dermatomyositis (JDM) is the most common inflammatory myopathy in pediatrics. This study evaluates the role of Natural Killer (NK) cells in Juvenile Dermatomyositis (JDM) pathophysiology. The study included 133 untreated JDM children with an NK cell count evaluation before treatment. NK cell subsets (CD56low/dim vs. CD 56bright) were examined in 9 untreated children. CD56 and perforin were evaluated in situ in six untreated JDM and three orthopedic, pediatric controls. 56% of treatment-naive JDM had reduced circulating NK cell counts, designated "low NK cell". This low NK group had more active muscle disease compared to the normal NK cell group. The percentage of circulating CD56low/dim NK cells was significantly lower in the NK low group than in controls (0.55% vs. 4.6% p < 0.001). Examination of the untreated JDM diagnostic muscle biopsy documented an increased infiltration of CD56 and perforin-positive cells (p = 0.023, p = 0.038, respectively). Treatment-naive JDM with reduced circulating NK cell counts exhibited more muscle weakness and higher levels of serum muscle enzymes. Muscle biopsies from treatment-naive JDM displayed increased NK cell infiltration, with increased CD56 and perforin-positive cells.

Increased Otoferlin Expression in B Cells Is Associated with Muscle Weakness in Untreated Juvenile Dermatomyositis: A Pilot Study.

Otoferlin mRNA expression is increased in JDM patients' PBMCs and muscle compared to healthy controls. This study aims to evaluate the role of otoferlin in JDM disease pathophysiology and its association with disease activity in untreated children with JDM. A total of 26 untreated JDM (88.5% female, 92.3% white, non-Hispanic) and 15 healthy controls were included in this study. Otoferlin mRNA expression was determined by qRT-PCR before and a few months after therapy. Detailed flow cytometry of various cell surface markers and cytoplasmic otoferlin was performed to identify cells expressing otoferlin. In addition, muscle otoferlin expression was evaluated in situ in six untreated JDM patients and three healthy controls. There was a significant increase in otoferlin expression in JDM children compared to controls (Median 67.5 vs. 2.1; p = 0.001). There was a positive correlation between mRNA otoferlin expression and the following disease activity markers: disease activity scores (DAS)-total (rs = 0.62, p < 0.001); childhood myositis assessment scale (CMAS) (rs = -0.61, p = 0.002); neopterin (rs = 0.57, p = 0.004) and von Willebrand factor antigen (vWF: Ag) (rs = 0.60, p = 0.004). Most of the otoferlin-positive cells were unswitched B cells (63-99.4%), with 65-75% of them expressing plasmablast markers (CD19+, IgM+, CD38hi, CD24-). The findings of this pilot study suggest that otoferlin expression is associated with muscle weakness, making it a possible biomarker of disease activity. Additionally, B cells and plasmablasts were the primary cells expressing otoferlin.

Adoptive T-Cell Transfer to Treat Lymphangioleiomyomatosis.

Patients with lymphangioleiomyomatosis (LAM) develop pulmonary cysts associated with neoplastic, smooth muscle-like cells that feature neuroendocrine cell markers. The disease preferentially affects premenopausal women. Existing therapeutics do not cure LAM. As gp100 is a diagnostic marker expressed by LAM lesions, we proposed to target this immunogenic glycoprotein using TCR transgenic T cells. To reproduce the genetic mutations underlying LAM, we cultured Tsc2-/- kidney tumor cells from aged Tsc2 heterozygous mice and generated a stable gp100-expressing cell line by lentiviral transduction. T cells were isolated from major histocompatibility complex-matched TCR transgenic pmel-1 mice to measure cytotoxicity in vitro, and 80% cytotoxicity was observed within 48 hours. Antigen-specific cytotoxicity was likewise observed using pmel-1 TCR-transduced mouse T cells, suggesting that transgenic T cells may likewise be useful to treat LAM in vivo. On intravenous injection, slow-growing gp100+ LAM-like cells formed lung nodules that were readily detectable in severe combined immunodeficient/beige mice. Adoptive transfer of gp100-reactive but not wild-type T cells into mice significantly shrunk established lung tumors, even in the absence of anti-PD-1 therapy. These results demonstrate the treatment potential of adoptively transferred T cells to eliminate pulmonary lesions in LAM.

The convergence theory for vitiligo: A reappraisal.

Vitiligo is characterized by progressive loss of skin pigmentation. The search for aetiologic factors has led to the biochemical, the neurologic and the autoimmune theory. The convergence theory was then proposed several years ago to incorporate existing theories of vitiligo development into a single overview of vitiligo aetiology. The viewpoint that vitiligo is not caused only by predisposing mutations, or only by melanocytes responding to chemical/radiation exposure, or only by hyperreactive T cells, but rather results from a combination of aetiologic factors that impact melanocyte viability, has certainly stood the test of time. New findings have since informed the description of progressive depigmentation. Understanding the relative importance of such aetiologic factors combined with a careful selection of the most targetable pathways will continue to drive the next phase in vitiligo research: the development of effective therapeutics. In that arena, it is likewise important to acknowledge that pathways affected in some patients may not be altered in others. Taken together, the convergence theory continues to provide a comprehensive viewpoint of vitiligo aetiology. The theory serves to intertwine aetiologic pathways and will help to define pathways amenable to disease intervention in individual patients.

Correction to: Clinical and immunologic evaluation of three metastatic melanoma patients treated with autologous melanoma-reactive TCR-transduced T cells.

The authors would like to make the following corrections to the published article.

Clinical and immunologic evaluation of three metastatic melanoma patients treated with autologous melanoma-reactive TCR-transduced T cells.

Malignant melanoma incidence has been increasing for over 30 years, and despite promising new therapies, metastatic disease remains difficult to treat. We describe preliminary results from a Phase I clinical trial (NCT01586403) of adoptive cell therapy in which three patients received autologous CD4+ and CD8+ T cells transduced with a lentivirus carrying a tyrosinase-specific TCR and a marker protein, truncated CD34 (CD34t). This unusual MHC Class I-restricted TCR produces functional responses in both CD4+ and CD8+ T cells. Parameters monitored on transduced T cells included activation (CD25, CD69), inhibitory (PD-1, TIM-3, CTLA-4), costimulatory (OX40), and memory (CCR7) markers. For the clinical trial, T cells were activated, transduced, selected for CD34t+ cells, then re-activated, and expanded in IL-2 and IL-15. After lymphodepleting chemotherapy, patients were given transduced T cells and IL-2, and were followed for clinical and biological responses. Transduced T cells were detected in the circulation of three treated patients for the duration of observation (42, 523, and 255 days). Patient 1 tolerated the infusion well but died from progressive disease after 6 weeks. Patient 2 had a partial response by RECIST criteria then progressed. After progressing, Patient 2 was given high-dose IL-2 and subsequently achieved complete remission, coinciding with the development of vitiligo. Patient 3 had a mixed response that did not meet RECIST criteria for a clinical response and developed vitiligo. In two of these three patients, adoptive transfer of tyrosinase-reactive TCR-transduced T cells into metastatic melanoma patients had clinical and/or biological activity without serious adverse events.

Alpha-N-acetyl-neuraminide alpha-2,8-sialyltransferase 1 can support immune responses toward tumors overexpressing ganglioside D3 in mice.

An immunotherapeutic strategy is discussed supporting anti-tumor activity toward malignancies overexpressing ganglioside D3. GD3 can be targeted by NKT cells when derived moieties are presented in the context of CD1d. NKT cells can support anti-tumor responses by secreting inflammatory cytokines and through cytotoxicity toward CD1d+GD3+ tumors. To overexpress GD3, we generated expression vector DNA and an adenoviral vector encoding the enzyme responsible for generating GD3 from its ubiquitous precursor GM3. We show that DNA encoding α-N-acetyl-neuraminide α-2,8-sialyltransferase 1 (SIAT8) introduced by gene gun vaccination in vivo leads to overexpression of GD3 and delays tumor growth. Delayed tumor growth is dependent on CD1d expression by host immune cells, as shown in experiments engaging CD1d knockout mice. A trend toward greater NKT cell populations among tumor-infiltrating lymphocytes is associated with SIAT8 vaccination. A single adenoviral vaccination introduces anti-tumor activity similarly to repeated vaccination with naked DNA. Here, greater NKT tumor infiltrates were accompanied by marked overexpression of IL-17 in the tumor, later switching to IL-4. Our results suggest that a single intramuscular adenoviral vaccination introduces overexpression of GD3 by antigen-presenting cells at the injection site, recruiting NKT cells that provide an inflammatory anti-tumor environment. We propose adenoviral SIAT8 (AdV-SIAT8) can slow the growth of GD3 expressing tumors in patients.

Replenishing Regulatory T Cells to Halt Depigmentation in Vitiligo.

Vitiligo is a cutaneous autoimmune disease, especially devastating to patients with darker skin tones because of the contrast between unaffected and lesional skin. We studied immune cells infiltrating vitiligo skin and found very few regulatory T cells (Tregs). Vitiligo was not associated with a reduced frequency or function of circulating Tregs. To manipulate Treg function, we used mouse models expressing melanocyte-reactive TCRs, following changes in pelage color. We also isolated splenocytes to measure Treg function and evaluated cutaneous Treg abundance. Even small numbers of Tregs transferred into depigmenting mice could effectively interfere with depigmentation. The same holds true for treatment with rapamycin, readily translatable for use in human patients; such treatment may be well tolerated. Because vitiligo skin is relatively devoid of cells that produce the chemokine CCL22, whereas circulating Tregs express normal levels of its receptor CCR4, we overexpressed Ccl22 in the skin of vitiligo-prone mice to assess the resulting levels of depigmentation. Markedly reduced depigmentation was accompanied by Treg infiltration to the skin. With several options available to support a healthy balance between Tregs and effector T cells, the next challenge will be to render such treatment antigen specific and avoid general immunosuppression.

Positioning ganglioside D3 as an immunotherapeutic target in lymphangioleiomyomatosis.

Tumors that develop in lymphangioleiomyomatosis (LAM) as a consequence of biallelic loss of TSC1 or TSC2 gene function express melanoma differentiation antigens. However, the percentage of LAM cells expressing these melanosomal antigens is limited. Here, we report the overexpression of ganglioside D3 (GD3) in LAM. GD3 is a tumor-associated antigen otherwise found in melanoma and neuroendocrine tumors; normal expression is largely restricted to neuronal cells in the brain. We also observed markedly reduced serum antibody titers to GD3, which may allow for a population of GD3-expressing LAM cells to expand within patients. This is supported by the demonstrated sensitivity of cultured LAM cells to complement mediated cytotoxicity via GD3 antibodies. GD3 can serve as a natural killer T (NKT) cell antigen when presented on CD1d molecules expressed on professional antigen-presenting cells. Although CD1d-expressing monocyte derivatives were present in situ, enhanced NKT-cell recruitment to LAM lung was not observed. Cultured LAM cells retained surface expression of GD3 over several passages and also expressed CD1d, implying that infiltrating NKT cells can be directly cytotoxic toward LAM lung lesions. Immunization with antibodies to GD3 may thus be therapeutic in LAM, and enhancement of existing NKT-cell infiltration may be effective to further improve antitumor responses. Overall, we hereby establish GD3 as a suitable target for immunotherapy of LAM.

Vitiligo treatment demystified: a flowchart for stratified treatment approaches.

The recent publication by Anbar et al. in the April issue of this journal, delineating and prioritizing treatment options for vitiligo, is both timely and significant. First and foremost, this work brings to the forefront the important message that vitiligo truly is a treatable disease. All too often, patients refrain from seeking treatment as public opinion dictates that vitiligo is not an important disease, there are no effective treatments available, and insurance will not cover attempts to treat. By providing clear guidelines of treatments to be considered, practicing physicians seeing an occasional vitiligo patient will be more readily inclined to explore the possibilities currently available for enhancing the quality of life of this patient group.

Enhanced bleaching treatment: opportunities for immune-assisted melanocyte suicide in vitiligo.

Depigmentation in vitiligo occurs by progressive loss of melanocytes from the basal layer of the skin, and can be psychologically devastating to patients. T cell-mediated autoimmunity explains the progressive nature of this disease. Rather than being confronted with periods of rapid depigmentation and bouts of repigmentation, patients with long-standing, treatment-resistant vitiligo can undergo depigmentation treatment. The objective is to remove residual pigmentation to achieve a cosmetically acceptable result--that of skin with a uniform appearance. In the United States, only the use of mono-benzyl ether of hydroquinone (MBEH) is approved for this purpose. However, satisfactory results can take time to appear, and there is a risk of repigmentation. MBEH induces necrotic melanocyte death followed by a cytotoxic T-cell response to remaining, distant melanocytes. As cytotoxic T-cell responses are instrumental to depigmentation, we propose that combining MBEH with immune adjuvant therapies will accelerate immune-mediated melanocyte destruction to achieve faster, more definitive depigmentation than with MBEH alone. As Toll-like Receptor (TLR) agonists--imiquimod, CpG, and Heat Shock Protein 70 (HSP 70)--all support powerful Th1 responses, we propose that using MBEH in combination with these agents can achieve superior depigmentation results for vitiligo patients.

Targeting melanocyte and melanoma stem cells by 8-hydroxy-2-dipropylaminotetralin.

Monobenzyl ether of hydroquinone (MBEH) is cytotoxic towards melanocytes. Its treatment efficacy is limited by an inability to eradicate stem cells. By contrast, 8-hydroxy-N,N-dipropyl-2-aminotetralin (8-DPAT) affects melanocyte stem cell survival. MBEH and 8-DPAT were added to melanocytes and melanoma cells to compare cytotoxicity. Stem cell content among viable cells was determined by fluorocytometry using markers CD34, Pax3, and CD271. Immunostaining was used to identify stem cells in skin explants treated with MBEH or 8-DPAT ex vivo. Mice were exposed to MBEH or 8-DPAT and scanned for depigmentation before harvesting skin. MBEH exposure prompted a relative increase in stem cells among cultured melanocytes and melanoma cells, as treatment preferentially eliminated differentiated cells and spared the stem cells. Viability of this remaining, enriched stem cell population was however rapidly reduced by exposure to 8-DPAT within melanocyte and melanoma cell cultures. In human skin explants, the abundance of melanocyte stem cells was also visibly reduced after 8-DPAT treatment, in contrast to tissue exposed to MBEH. Meanwhile, significant depigmentation of the mouse pelage and loss of differentiated melanocytes was observed in vivo in response to topical application of MBEH, but not 8-DPAT. Prolonged application of the latter agent instead appeared to effectively reduce the abundance of melanocyte stem cells in the dermis. This furthers the idea that MBEH and 8-DPAT target complementary cell populations. Results indicate that combination treatment may demonstrate superior therapeutic activity by eliminating both differentiated and tumor initiating populations.

A coreceptor-independent transgenic human TCR mediates anti-tumor and anti-self immunity in mice.

Recent advancements in T cell immunotherapy suggest that T cells engineered with high-affinity TCR can offer better tumor regression. However, whether a high-affinity TCR alone is sufficient to control tumor growth, or the T cell subset bearing the TCR is also important remains unclear. Using the human tyrosinase epitope-reactive, CD8-independent, high-affinity TCR isolated from MHC class I-restricted CD4(+) T cells obtained from tumor-infiltrating lymphocytes (TIL) of a metastatic melanoma patient, we developed a novel TCR transgenic mouse with a C57BL/6 background. This HLA-A2-restricted TCR was positively selected on both CD4(+) and CD8(+) single-positive cells. However, when the TCR transgenic mouse was developed with a HLA-A2 background, the transgenic TCR was primarily expressed by CD3(+)CD4(-)CD8(-) double-negative T cells. TIL 1383I TCR transgenic CD4(+), CD8(+), and CD4(-)CD8(-) T cells were functional and retained the ability to control tumor growth without the need for vaccination or cytokine support in vivo. Furthermore, the HLA-A2(+)/human tyrosinase TCR double-transgenic mice developed spontaneous hair depigmentation and had visual defects that progressed with age. Our data show that the expression of the high-affinity TIL 1383I TCR alone in CD3(+) T cells is sufficient to control the growth of murine and human melanoma, and the presence or absence of CD4 and CD8 coreceptors had little effect on its functional capacity.

Vitiligo: advances in pathophysiology research and treatment development.

The autoimmune condition vitiligo, characterized by skin depigmentation, presents challenges for effective treatment design, with Janus kinase (JAK) inhibitors and other repurposed drugs offering a promising strategy for symptom management. This review explores advantages and shortcomings of current therapies, while presenting the urgent need for further innovative approaches. We emphasize the growing understanding of autoimmune involvement in vitiligo, highlighting several novel treatment avenues including relieving melanocyte stress, preventing dendritic cell activation, halting T cell migration, and suppressing inflammation and autoimmunity. Integrating psychodrama therapy to remediate stress alongside medical interventions marks a holistic approach to enhance patient well-being. The molecular underpinnings of vitiligo care are covered, emphasizing exciting advances revolutionizing vitiligo treatment and improving the quality of life for affected individuals.

Topical antibiotics limit depigmentation in a mouse model of vitiligo.

Oral neomycin administration impacts the gut microbiome and delays vitiligo development in mice, and topical antibiotics may likewise allow the microbiome to preserve skin health and delay depigmentation. Here, we examined the effects of 6-week topical antibiotic treatment on vitiligo-prone pmel-1 mice. Bacitracin, Neosporin, or Vaseline were applied to one denuded flank, while the contralateral flank was treated with Vaseline in all mice. Ventral depigmentation was quantified weekly. We found that topical Neosporin treatment significantly reduced depigmentation and exhibited effects beyond the treated area, while Bacitracin ointment had no effect. Stool samples collected from four representative mice/group during treatment revealed that Neosporin treatment aligned with reduced abundance of the Alistipes genus in the gut, while relevant changes to the skin microbiome at end point were less apparent. Either antibiotic treatment led to reduced expression of MR1, potentially limiting mucosal-associated invariant T-cell activation, while Neosporin-treated skin selectively revealed significantly reduced CD8+ T-cell abundance. The latter finding aligned with reduced expression of multiple inflammatory markers and markedly increased regulatory T-cell density. Our studies on favorable skin and oral antibiotic treatment share the neomycin compound, and in either case, microbial changes were most apparent in stool samples. Taken together, neomycin-containing antibiotic applications can mediate skin Treg infiltration to limit vitiligo development. Our study highlights the therapeutic potential of short-term antibiotic applications to limit depigmentation vitiligo.

Immune Assessment Today: Optimizing and Standardizing Efforts to Monitor Immune Responses in Cancer and Beyond.

As part of a symposium, current and former directors of Immune Monitoring cores and investigative oncologists presented insights into the past, present and future of immune assessment. Dr. Gnjatic presented a classification of immune monitoring technologies ranging from universally applicable to experimental protocols, while emphasizing the need for assay harmonization. Dr. Obeng discussed physiologic differences among CD8 T cells that align with anti-tumor responses. Dr. Lyerly presented the Soldano Ferrone lecture, commemorating the passionate tumor immunologist who inspired many, and covered a timeline of monitoring technology development and its importance to immuno-oncology. Dr. Sonabend presented recent achievements in glioblastoma treatment, accentuating the range of monitoring techniques that allowed him to refine patient selection for clinical trials. Dr. Guevara-Patiño focused on hypoxia within the tumor environment and stressed that T cell viability is not to be confused with functionality. Dr. Butterfield accentuated monitoring of dendritic cell metabolic (dys)function as a determinant for tumor vaccine success. Lectures were interspersed with select abstract presentations. To summarize the concepts, Dr. Maecker from Stanford led an informative forum discussion, pointing towards the future of immune monitoring. Immune monitoring continues to be a guiding light towards effective immunotherapeutic strategies.

A central role for inducible heat-shock protein 70 in autoimmune vitiligo.

Inducible heat-shock protein 70 (HSP70i) is a protein regulated by stress that protects cells from undergoing apoptosis. Such proteins are marvellously well conserved throughout evolution, which has placed them in the spotlight for helping to understand the intriguing relationship between infection and immunity. In the presence of stress proteins, dendritic cells (DCs) will sense this alarm signal and respond by recruiting immune cells of different plumage to fit the occasion. In times of stress, melanocytes will secrete antigen-bound HSP70i to act as an alarm signal in activating DCs that comes equipped with an address of origin to drive the autoimmune response in vitiligo. Here we pose that if the autoimmune response is funnelled through HSP70i, then blocking the stress protein from activating DCs can lend new treatment opportunities for vitiligo.

Notch signaling regulates mouse and human Th17 differentiation.

Th17 cells are known to play a critical role in adaptive immune responses to several important extracellular pathogens. Additionally, Th17 cells are implicated in the pathogenesis of several autoimmune and inflammatory disorders as well as in cancer. Therefore, it is essential to understand the mechanisms that regulate Th17 differentiation. Notch signaling is known to be important at several stages of T cell development and differentiation. In this study, we report that Notch1 is activated in both mouse and human in vitro-polarized Th17 cells and that blockade of Notch signaling significantly downregulates the production of Th17-associated cytokines, suggesting an intrinsic requirement for Notch during Th17 differentiation in both species. We also present evidence, using promoter reporter assays, knockdown studies, as well as chromatin immunoprecipitation, that IL-17 and retinoic acid-related orphan receptor γt are direct transcriptional targets of Notch signaling in Th17 cells. Finally, in vivo inhibition of Notch signaling reduced IL-17 production and Th17-mediated disease progression in experimental autoimmune encephalomyelitis, a mouse model of multiple sclerosis. Thus, this study highlights the importance of Notch signaling in Th17 differentiation and indicates that selective targeted therapy against Notch may be an important tool to treat autoimmune disorders, including multiple sclerosis.

Acceleration of melanocyte senescence by the proinflammatory cytokines IFNγ and TNFα impairs the repigmentation response of vitiligo patients to narrowband ultraviolet B (NBUVB) phototherapy.

Vitiligo is a chronic autoimmune disease characterized by the T helper 1 (Th1) cytokine-driven immune destruction of melanocytes (MCs). Although narrowband ultraviolet B (NBUVB) phototherapy has been proven to be an effective therapeutic option, the repigmentation response to that phototherapy varies greatly in different vitiligo patients. Here, we demonstrate that there is an increase of NBUVB-induced cellular senescence in vitiligo MCs exposed to Th1 cytokine interferon γ (IFNγ) and/or tumor necrosis factor α (TNFα) in lesional vitiligo skin from poor responders who had undergone NBUVB phototherapy. Supplementation with exogenous recombinant human stem cell factor (rhSCF) in the culture medium as well as the lentiviral vector-mediated overexpression of cKIT could prevent the MCs from the IFNγ/TNFα-accelerated cellular senescence. Mechanistic studies indicated that the reduced ratio of membrane-bound KIT (mKIT) to the soluble form of KIT (sKIT) is directly related to the cellular senescence of vitiligo MCs following exposure to IFNγ and TNFα. Furthermore, the matrix metalloprotease 9 (MMP9) inhibitor GM6001 attenuates the production of sKIT via the suppression of cKIT ectodomain shedding. Altogether, our study indicates that the presence of Th1 cytokines IFNγ and/or TNFα in the epidermal milieu might impair the repigmentation response of vitiligo patients to NBUVB phototherapy.

Melanocyte-keratinocyte cross-talk in vitiligo.

Vitiligo is a common acquired pigmentary disorder that presents as progressive loss of melanocytes from the skin. Epidermal melanocytes and keratinocytes are in close proximity to each other, forming a functional and structural unit where keratinocytes play a pivotal role in supporting melanocyte homeostasis and melanogenesis. This intimate relationship suggests that keratinocytes might contribute to ongoing melanocyte loss and subsequent depigmentation. In fact, keratinocyte dysfunction is a documented phenomenon in vitiligo. Keratinocyte apoptosis can deprive melanocytes from growth factors including stem cell factor (SCF) and other melanogenic stimulating factors which are essential for melanocyte function. Additionally, keratinocytes control the mobility/stability phases of melanocytes via matrix metalloproteinases and basement membrane remodeling. Hence keratinocyte dysfunction may be implicated in detachment of melanocytes from the basement membrane and subsequent loss from the epidermis, also potentially interfering with repigmentation in patients with stable disease. Furthermore, keratinocytes contribute to the autoimmune insult in vitiligo. Keratinocytes express MHC II in perilesional skin and may present melanosomal antigens in the context of MHC class II after the pigmented organelles have been transferred from melanocytes. Moreover, keratinocytes secrete cytokines and chemokines including CXCL-9, CXCL-10, and IL-15 that amplify the inflammatory circuit within vitiligo skin and recruit melanocyte-specific, skin-resident memory T cells. In summary, keratinocytes can influence vitiligo development by a combination of failing to produce survival factors, limiting melanocyte adhesion in lesional skin, presenting melanocyte antigens and enhancing the recruitment of pathogenic T cells.