Asthmatic bronchial epithelium activated by the proteolytic allergen Der p 1 increases selective dendritic cell recruitment

BACKGROUND: Airway dendritic cells (DCs) are crucial for allergen-induced sensitization and inflammation in allergic asthma. After allergen challenge, an increased number of DCs is observed in airway epithelium from patients with allergy. OBJECTIVE: Because Der p 1, a cysteine protease allergen from Dermatophagoides pteronyssinus , induces chemokine production by bronchial epithelial cells (BECs), the purpose of this investigation was to evaluate the capacity of BEC exposed to Der p 1 to recruit DCs. METHODS: Chemotactic activity of BEAS-2B, a bronchial epithelial cell line, and BECs from nonatopic controls and patients with allergic asthma was evaluated on the migration of precursors, immature and mature monocyte-derived DCs (MDDCs), and CD34 + -derived Langerhans cells (LCs). RESULTS: C-C chemokine ligand (CCL)-2, CCL5, and C-X-C chemokine ligand 10 production by BEAS-2B and BEC was increased after Der p 1 exposure, whereas the proenzyme proDer p 1 devoid of enzymatic activity had no effect. Der p 1 stimulation of BEAS-2B and BEC from both groups increased significantly the recruitment of MDDC precursors, depending on CCL2, CCL5, and C-X-C chemokine ligand 10 production. In a reconstituted polarized epithelium, apical application of Der p 1 enhanced MDDC precursor migration into the epithelial layer. Moreover, Der p 1 stimulation of BEC from patients with asthma but not from controls increased the migration of LC precursors, mainly dependent on CCL20 secretion. No migration of immature and mature DCs was observed. CONCLUSION: These data confirmed that BECs participate in the homeostasis of the DC network present within the bronchial epithelium through the secretion of chemokines. In allergic asthma, upregulation of CCL20 production induced LC recruitment, the role of which remains to be determined.     

Toll-like receptor agonists differentially regulate cysteinyl-leukotriene receptor 1 expression and function in human dendritic cells

BACKGROUND: Dendritic cells (DCs) acquire, during their maturation, the expression of the chemokine receptor CCR7 and the ability to migrate to lymph nodes in response to CC chemokine ligand 19 (CCL19). This migration is impaired in mice lacking the leukotriene (LT) C4 transporter and restored by addition of exogenous LTC4. OBJECTIVE: To define the role of LT in human DC function, we studied the expression and function of the cysteinyl-leukotriene (CysLT) receptors during DC differentiation from monocytes and subsequent maturation. METHODS: Receptor expression was measured by flow cytometry and real-time PCR. Responsiveness to LTD4 stimulation was assessed by calcium flux and chemotaxis. RESULTS: Maturation of DC with LPS, a classic Toll-like receptor 4 agonist, reduced CysLT receptor 1 (CysLT1) expression by 50%, whereas CysLT receptor 2 expression was increased. In contrast, the Toll-like receptor 3 agonist poly inosinic and cytidylic acid (polyI:C) had no effect on receptor expression. Downregulation of CysLT1 expression by LPS could not be mimicked by TNF-alpha alone or in combination with IL-1beta or IL-6. It was, however, prevented by inhibitors of COX and could be reproduced by a combination of TNF-alpha and prostaglandin E2. Immature DCs and DCs matured with polyI:C, but not with LPS, responded to LTD4 with a robust cytosolic calcium flux, which was prevented by the CysLT1 antagonist montelukast. LTD4 induced DC chemotaxis and enhanced DC migration in response to CCL19 in DCs matured with polyI:C, but only weakly in DCs matured with LPS. CONCLUSION: Our data suggest that human DCs may differentially respond to leukotriene, depending on their maturational stimuli. CLINICAL IMPLICATIONS: Our study demonstrates that some microbial agents can reduce the migration of dendritic cells in response to leukotrienes, with potential for differential involvement of these cells in allergic inflammation.     

Tumour-loaded α-type 1-polarized dendritic cells from patients with chronic lymphocytic leukaemia produce a superior NK-, NKT- and CD8+ T cell-attracting chemokine profile

Tumour-loaded dendritic cells (DCs) from patients with chronic lymphocytic leukaemia (CLL) matured using an α-type 1-polarized DC cocktail (IL-1β/TNF-α/IFN-α/IFN-γ/poly-I:C;αDC1) were recently shown to induce more functional CD8(+) T cells against autologous tumour cells in vitro than DCs matured with the 'standard' cocktail (IL-1β/TNF-α/IL-6/PGE(2) ;PGE(2) DCs). However, the ability of vaccine DCs to induce a type 1-polarized immune response in vivo probably relies on additional features, including their ability to induce a CXCR3-dependent recruitment of NK cells into vaccine-draining lymph nodes. Moreover, their guiding of rare tumour-specific CD8(+) T cells to sites of DC-CD4(+) T cell interactions by secretion of CCL3 and CCL4 is needed. We therefore analysed the chemokine profile and the lymphocyte-attracting ability in vitro of monocyte-derived PGE(2) DCs and αDC1s from patients with CLL. αDC1s produced much higher levels of CXCR3 ligands (CXCL9/CXCL10/CXCL11) than PGE(2) DCs. Functional studies further demonstrated that αDC1s were superior recruiters of both NK and NKT cells. Moreover, αDC1s produced higher levels of CCL3/CCL4 upon CD40 ligation. These findings suggest that functional αDC1s, derived from patients with CLL, produce a desirable NK-, NKT- and CD8(+) T cell-attracting chemokine profile which may favour a guided and Th1-deviated priming of CD8(+) T cells, supporting the idea that αDC1-based vaccines have a higher immunotherapeutic potential than PGE(2) DCs.     

Sjögren's syndrome autoantibodies provoke changes in gene expression profiles of inflammatory cytokines triggering a pathway involving TACE/NF-κB

We explore the association of the inflammatory gene expression profile observed in the chronic inflammatory autoimmune disorder Sj?gren's syndrome (SS) with changes in TNF-α converting enzyme (TACE), tumor necrosis factor (TNF)-α and nuclear factor (NF)-κB levels showing that pathways that include TNF-α signaling converge on NF-κB contributing to exacerbate the diseases. The treatment of human salivary gland epithelial cells (SGECs) with SS anti-Ro/SSA autoantibodies (Abs) result in a progressive increase in NF-κB-DNA binding, that includes a marked enhancement in NF-κB subunit p65 protein-DNA binding. A human cytokine multi-analyte array demonstrated that the NF-κB proinflammatory target genes, increased by anti-Ro/SSA Abs treatment, includes CXC chemokines (CXCL1, CXCL6 and CXCL9), CC chemokines (CCL2, CCL13 and CCL20), interleukins (IL-1α, IL-1β, IL-1F8, IL-6, IL-8, IL-9, IL-13, IL-17 and IL-22) and their receptors (IL-1RN, IL-10Rα, IL-13Rα, CCR1, CCR2, CCR3, CCR4 and CXCR1). Blockade of TACE through the use of the specific inhibitor TAPI-1 regulates proinflammatory cytokines production in SGEC treated with anti-Ro/SSA Abs inhibiting NF-κB nuclear translocation and activation. To further investigate the role of NF-κB on anti-Ro/SSA Abs-determined proinflammatory gene expression, we used the inhibitory protein IκB-α dominant negative super-repressor as inhibitor of NF-κB-DNA binding, demonstrating that transfection with dominant-negative IκB-α in anti-Ro/SSA-treated SGEC determined a marked reduction of proinflammatory cytokines gene expression. Although further studies are needed to clarify the mechanisms underlying SS, our results demonstrate that SS Abs exert their pathogenic effects via triggering the TACE/TNF-α/NF-κB axis.     

Distinct effect of CD40 and TNF-signaling on the chemokine/chemokine receptor expression and function of the human monocyte-derived dendritic cells

A key and limiting step in the process of human monocyte-derived dendritic cells （mDCs） for clinical use is their in vitro maturation and in vivo migration. We previously observed that CD40 signal facilitated human mDC growth and maturation. To further explore this process, mDCs generated with GM-CSF and IL-4 were co-cultured with apoptotic tumor cells for 24 hours, followed by incubating with anti-CD40 monoclonal antibody or TNF-a for 48 hours to generate mature DCs. The chemokine/chemokine receptor expression and functions of mature DCs upon various stimuli were determined. The expression of costimulatory molecules on apoptotic tumor cell-loaded mature DCs co-cultured with either anti-CD40 antibody （anti-CD40-DCs） or TNF-a （TNF-DCs） were up-regulated compared to immature DCs, consistent with the abilities of these cytokine to drive DC maturation in vitro. The mRNA levels of chemokines such as stromal cell-derived factor-1a （SDF-1a）, EBV-induced molecule 1 ligand chemokine （ELC）, and IFN inducible protein-10 （IP-10） in anti-CD40 activated DCs were increased and the dendritic cell-specific chemokine 1 （DC-CK1） was moderately up-regulated as compared with other mature DCs. The corresponding chemokine receptors CXCR4 and CCR7 of anti-CD40-DCs were significantly expressed. The CXCR3 expression on activated T cells stimulated by anti-CD40-DCs was also increased. Moreover, the anti-CD40-DCs had a stronger ability to stimulate T cell proliferation than any other DCs. The NF-xB activity was much higher in anti-CD40-DCs than that of TNF-DCs. These results offer further evidence of the importance of the CD40 signal in developing efficient human DC vaccines for cancer immune therapy. Cellular ＆ Molecular Immunology.     

Maturation of human iDCs by IL-18 plus PGE2, but not by each stimulus alone,induced migration toward CCL21 and the secretion of IL-12 and IFN-γ

Dendritic cells (DCs) are potent antigen-presenting cells that initiate the primary immune response and whose functional properties in vivo depend on the maturation stimulus. We describe the functional properties of human monocyte-derived DCs after the maturation of immature DCs (iDCs) for 2 days with LPS (100 ng/ml), PGE2 (1 μg/ml), CD40L (1 μg/ml) or IL-18 (200 ng/ml) and with CD40L + PGE2 and IL-18 + PGE2 mixtures at the same concentrations as above. Neither IL-18 nor PGE2 alone stimulated IL-12 or IFN-γ secretion. When administered simultaneously to 1 × 10⁶ iDCs/ml, IL-18 + PGE2 induced the secretion of 131.4 ± 6.7 pg IL-12/ml and 355 ± 87 pg IFN-γ/ml but there was no detectable IL-10 secretion. However, PGE2 alone stimulated the secretion of 208 ± 89 pg IL-10/ml whereas IL-18 alone did not stimulate the secretion of IL-10, IL-12, TNF-α or INF-γ. When the mixture of CD40L + PGE2 was used, only migration toward CCL19 and CCL21 was induced. CD40L did not stimulate the secretion of IL-10, IL-12, TNF-α or IFN-γ and did not stimulate migration toward CCL19 or CCL21. The extent of stimulation of T cell proliferation was essentially the same for all stimuli at the concentrations given above. New properties such as IL-12 and INF-γ secretion and migration toward CCL21 emerged when a mixture of IL-18 + PGE2 was employed. These data show that when the pairs of stimuli reported here were used simultaneously their effect was not additive. This system can be used to prepare mDCs with properties useful for cell therapy and also as a model to investigate the mechanisms of cytokine secretion and cell migration.     

Regulatory role of nitric oxide on monocyte-derived dendritic cell functions.

Nitric oxide (NO) has an established role in the defense against bacterial infections and exerts multiple modulatory activities on both inflammatory and immune responses. However, the relevance of NO on dendritic cell (DC) functions has been poorly investigated. In this study, we found that addition of the NO donor S-nitrosoglutathione (GSNO) to monocyte-derived DCs matured by lipopolysaccharide (LPS) or soluble CD40 ligand led to a decreased capacity to activate naive allogeneic T cells but a more prominent Th1 polarization, with increased interferon-gamma (IFN-gamma) secretion and reduced interleukin-5 (IL-5) release. The presence of GSNO during maturation of DCs caused a reduced expression of surface CD86, whereas CD80, CD83, and MHC molecule expression was not affected. Moreover, GSNO induced a dose-dependent decrease of IL-10 and enhancement of tumor necrosis factor-alpha (TNF-alpha) release from mature DCs. In parallel, a marked reduced production of IL-12 p40 subunit but no significant perturbation of the bioactive IL-12 p70 production was observed. Finally, GSNO significantly reduced the release of IP-10/CXCL10 and RANTES/CCL5 but not IL-8/CXCL8 by mature DCs. Although GSNO can strengthen the capacity of mature DCs to induce type 1 polarization of T lymphocytes, our data suggest that it elicits distinct anti-inflammatory functions, eventually reducing T lymphocyte proliferation and recruitment.     

IL-33 links tissue cells, dendritic cells and Th2 cell development in a mouse model of asthma

IL-33 is becoming a central molecule in allergic asthma that addresses various cascades of innate and adaptive immune responses that lead to inflammation in the lung. Its effects are exerted via its heterodimeric receptor that consists of ST2 and the ubiquitously expressed IL-1 receptor accessory protein (ILRAcP). IL-33 integrates both innate and adaptive immunity in a unique fashion via basophils, mast cells, eosinophils, innate lymphoid cells, NK and NKT cells, nuocytes, Th2 lymphocytes and a CD34(pos) precursor cell population. These actions of IL-33 seem to be particularly strong and dominant in models with mucosal inflammation. A study in this issue of the European Journal of Immunology demonstrates that IL-33 acts, in an ST2-dependent manner, as a maturation factor for BM-derived DCs via up-regulation of CD80, CD40 and OX40L. This process is accompanied by the release of pro-inflammatory cytokines, such as IL-6, IL-1β, TNF-α and TARC/CCL17. IL-33-pre-treated DCs were significantly more potent for the generation of allergen-specific Th2-type cells with IL-5 and IL-13 production. Intratracheal administration of OVA-pulsed DCs with IL-33 significantly enhances eosinophil numbers and mucous secretion. In conclusion, IL-33 affects both the development of allergic sensitization and the development of lung inflammation in allergic asthma.     

Airway epithelial cells release MIP-3alpha/CCL20 in response to cytokines and ambient particulate matter

The initiation and maintenance of airway immune responses in Th2 type allergic diseases such as asthma are dependent on the specific activation of local airway dendritic cells (DCs). The cytokine microenvironment, produced by local cells, influences the recruitment of specific subsets of immature DCs and their subsequent maturation. In the airway, DCs reside in close proximity to airway epithelial cells (AECs). We examined the ability of primary culture human bronchial epithelial cells (HBECs) to synthesize and secrete the recently described CC-chemokine, MIP-3alpha/CCL20. MIP-3alpha/CCL20 is the unique chemokine ligand for CCR6, a receptor with a restricted distribution. MIP-3alpha/CCL20 induces selective migration of DCs because CCR6 is expressed on some immature DCs but not on CD14+ DC precursors or mature DCs. HBECs were stimulated with pro-inflammatory cytokines tumor necrosis factor-alpha and interleukin (IL)-1beta or, because of their critical role in allergic diseases, IL-4 and IL-13. Cells were also exposed to small size-fractions of ambient particulate matter. Each of these stimuli induced MIP-3alpha/CCL20 gene and protein expression. Moreover, these agents upregulated mitogen-activated protein kinase pathways in HBECs. Inhibition of the ERK1/2 pathway or p38 reduced cytokine-induced MIP-3alpha/CCL20 expression. These data suggest a mechanism by which AEC may facilitate recruitment of DC subsets to the airway.     

Dendritic cells primed with HPV positive cervical tumor lysate are superior to unprimed DCs in migratory capacity and induce a potent Th1 response

In this study, we assessed the efficacy of tumor lysate primed and unprimed monocyte derived mature dendritic cells (DCs) to trigger an effective anti-tumor immune response in cervical cancer patients who tested positive for human papilloma virus (HPV) DNA. Lysate primed and unprimed DCs were assessed for the expression of CD80, CD86, CD40, HLADR and CD83. The ability of DCs to migrate in response to the chemokines CCL19 and 21 as well as their ability to secrete IL12p40 was investigated. Mixed lymphocyte proliferation assays were used to assess DC stimulatory capacity and their ability to generate a Th1 response. Our results showed no difference in phenotypic expression between primed and unprimed DCs but both had significantly increased expression of the activation marker CD83 when compared to immature DCs. Importantly, the primed DCs showed significant (P value = 0.03) IL-12p40 secretion and a superior migratory capacity towards CC19 and CCL21 (P value = 0.04) compared to unprimed DCs even after cytokine withdrawal. Primed DCs showed superior stimulation of T cell proliferation (allogeneic and autologous) and secretion of IFN gamma (IFN-γ) than the unprimed DCs. Hence whole tumor lysate primed mature DCs could be potent immunotherapeutic adjuvants to standard treatment for cervical cancer.     

Overexpression of B7-H4 in tumor infiltrated dendritic cells

DCs infiltrated tumors appears to be phenotypically and functionally defective. B7-H4 was highlighted for its inhibitory role in T cell responses. In this study, we showed that B7-H4 was moderately expressed in imDCs, and up-regulated by IL-10, and TNF-α could counteract the up-regulatory effects of IL-10 on expression of B7-H4 in DCs in vitro. Furthermore, tumor infiltrated DCs expressed B7-H4 at high levels. Blockade of B7-H4 expressed in DCs highly resulted in enhanced T cell proliferation and IFN-γ production significantly. Otherwise, the high level of IL-10 and TNF-α was both detected in the tumor, which suggested that TNF-α can not antagonize the effects of IL-10 on expression of B7-H4 in DCs in vivo. These data indicate that tumor environment may condition local DCs to become dysfunctional in the phenotype, and that the high expression of B7-H4 may contribute to the tumor infiltrated DCs to mediate immune invasion.     

B7-H1阻断对未成熟树突状细胞免疫功能的影响

目的：探讨B7-H1阻断对未成熟树突状细胞(DCs)的免疫刺激活性的影响。 方法： 以细胞因子GM-CSF和IL-4体外诱导人单核细胞来源的树突状细胞，流式细胞仪检测在诱导过程中B7-H1的表达，并以B7-H1单抗阻断处理，分别以流式细胞仪、MTT法、ELISA、ELISPOT法检测B7-H1阻断对DCs的成熟和内吞能力、刺激淋巴细胞增殖、IL-12的分泌、诱导淋巴细胞分化的影响。 结果： DCs在诱导过程中B7-H1表达逐渐增强，第7 d时的阳性表达率为54.12％，以TNF-α诱导成熟后阳性表达率为83.64％；B7-H1阻断对DCs成熟和内吞能力无影响，但可使未成熟DCs刺激淋巴细胞增殖的能力和IL-12的分泌明显增强，并诱导淋巴细胞向分泌IFN-γ的Th1/Tc1的分化。 结论： B7-H1阻断可增强未成熟DCs的免疫刺激活性，利用B7-H1阻断的DCs瘤苗激发抗肿瘤免疫的方案值得进一步探讨。     

IL-10 deficiency blocks the ability of LPS to regulate expression of tolerance-related molecules on dendritic cells

Interleukin-10 (IL-10) is an anti-inflammatory cytokine that plays an important role in regulating the local inflammatory immune response, but regulatory mechanisms of this cytokine have not been fully elucidated. Here, we demonstrate that IL-10 deficiency renders LPS treatment ineffective in regulating the expression of CD40, CD80, CD86, B7-H2, and B7-DC on dendritic cells (DCs) and blocks upregulation of IL-27. This inability to respond to LPS was found in both IL-10(-/-) bone marrow derived and splenic DCs. Compared with wild-type DCs, IL-10(-/-) DCs expressed similar levels of TLR4 and CD14, but produced less LPS-binding protein. The deficiency in LPS-binding protein production may explain the failure of IL-10(-/-) DCs to respond normally to LPS. Moreover, lack of IL-10 modulated the proportions of CD11c(+) CD8(+) and CD11c(+) B220(+) DCs, which play an important role in local inflammatory responses and tolerance. IL-10 deficiency also blocked expression of galectin-1, CD205, and CD103, which are necessary for central and peripheral tolerance. While they did not respond to LPS, IL-10(-/-) DCs produced increased levels of IL-6 and CCL4 after TNF-α treatment. Together, our results demonstrate that IL-10 deficiency affects the immune functions of DCs, which may contribute to the increased severity of autoimmune diseases seen in IL-10(-/-) mice.     

Potential autocrine regulation of interleukin-33/ST2 signaling of dendritic cells in allergic inflammation

This study identified a novel phenomenon that dendritic cells (DCs) produced interleukin (IL)-33 via Toll-like receptor (TLR)-mediated innate pathway. Mouse bone marrow–derived DCs were treated with or without microbial pathogens or recombinant murine IL-33. IL-33 mRNA and protein were found to be expressed by DCs and largely induced by several microbial pathogens, highly by lipopolysaccharide (LPS) and flagellin. Using two mouse models of topical challenge by LPS and flagellin and experimental allergic conjunctivitis, IL-33-producing DCs were observed in ocular mucosal surface and the draining cervical lymph nodes in vivo. The increased expression levels of myeloid differentiation primary-response protein 88 (MyD88), nuclear factor (NF)-κB1, NF-κB2, and RelA accompanied by NF-κB p65 nuclear translocation were observed in DCs exposed to flagellin. IL-33 induction by flagellin was significantly blocked by TLR5 antibody or NF-κB inhibitor quinazoline and diminished in DCs from MyD88 knockout mice. IL-33 stimulated the expression of DC maturation markers, CD40 and CD80, and proallergic cytokines and chemokines, OX40L, IL-4, IL-5, IL-13, CCL17 (C-C motif chemokine ligand 17), TNF-α (tumor necrosis factor-α), and IL-1β. This stimulatory effect of IL-33 in DCs was significantly blocked by ST2 antibody or soluble ST2. Our findings demonstrate that DCs produce IL-33 via TLR/NF-κB signaling pathways, suggesting a molecular mechanism by which local allergic inflammatory response may be amplified by DC-produced IL-33 through potential autocrine regulation.     

CCL19 and CCL21 induce a potent proinflammatory differentiation program in licensed dendritic cells

Dendritic cells (DCs) are key instigators of adaptive immune responses. Using an alphaviral expression cloning technology, we have identified the chemokine CCL19 as a potent inducer of T cell proliferation in a DC-T cell coculture system. Subsequent studies showed that CCL19 enhanced T cell proliferation by inducing maturation of DCs, resulting in upregulation of costimulatory molecules and the production of proinflammatory cytokines. Moreover, CCL19 programmed DCs for the induction of T helper type (Th) 1 rather than Th2 responses. Importantly, only activated DCs that migrated from the periphery to draining lymph nodes, but not resting steady-state DCs residing within lymph nodes, expressed high levels of CCR7 in vivo and responded to CCL19 with the production of proinflammatory cytokines. Migrating DCs isolated from mice genetically deficient in CCL19 and CCL21 (plt/plt) presented an only partially mature phenotype, highlighting the importance of these chemokines for full DC maturation in vivo. Our findings indicate that CCL19 and CCL21 are potent natural adjuvants for terminal activation of DCs and suggest that chemokines not only orchestrate DC migration but also regulate their immunogenic potential for the induction of T cell responses.     

Regulation of dendritic cell trafficking by the ADP-ribosyl cyclase CD38: impact on the development of humoral immunity

Mice lacking CD38, an ectoenzyme that generates the calcium-mobilizing metabolite cADPR, make reduced T cell-dependent antibody responses. Despite the predicted role for CD38 in B cell activation, we find that CD38 regulates the migration of dendritic cell (DC) precursors from the blood to peripheral sites and controls the migration of mature DCs from sites of inflammation to lymph nodes. Thus, T cells are inefficiently primed in Cd38(-/-) mice, leading to poor humoral immune responses. We also show that CD38 and cADPR modulate calcium mobilization in chemokine-stimulated DCs and are required for the chemotaxis of immature and mature DCs to CCL2, CCL19, CCL21, and CXCL12. Therefore, CD38 regulates adaptive immunity by controlling chemokine receptor signaling in DCs.     

TNF-α is essential in the induction of fatal autoimmune hepatitis in mice through upregulation of hepatic CCL20 expression

It is unclear what roles TNF-α has in the development of autoimmune hepatitis (AIH) and whether AIH is responsive to anti-TNF-α. We recently developed a mouse model of fatal AIH that develops in PD-1-deficient mice thymectomized three days after birth, finding that CCR6-CCL20 axis-dependent migration of dysregulated splenic T cells is crucial to induce AIH. In this study, we show the indispensable role of TNF-α in the development of AIH. Administering anti-TNF-α prevented the induction, but treatment by anti-TNF-α after the induction did not suppress progression. Administering anti-TNF-α did not prevent splenic T-cell activation, but did suppress hepatic CCL20 expression. In contrast, administering anti-CCL20 suppressed AIH but not elevated serum TNF-α levels. TNF-α stimulation enhanced CCL20 expression in hepatocytes. These findings suggest that TNF-α is essential in the induction of AIH through upregulation of hepatic CCL20 expression, which allows migration of dysregulated splenic T cells.