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Production by Memory CD4+ T Cells1
* Unité Mixte Institut National de la Santé et de la Recherche Médicale 564, University Hospital, Angers, France; Laboratoire d’Immunologie et d’Allergologie, University Hospital, Angers, France; and Etablissement Français du Sang Pays de la Loire, Angers, France
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Abstract |
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, IL-8, and IL-10 but not IL-4 production by human CD4+ T cells. No effect of poly(I:C) and LPS, ligands for TLR3 and TLR4, respectively, was detected. We also observed that CD4+CD45RO+ memory T cell responses to TLR ligands were more potent than those observed with CD4+CD45RA+ naive T cells. Moreover, among the memory T cells, CCR7– effector cells were more sensitive to TLR ligands than CCR7+ central memory cells. These data demonstrate for the first time a direct effect of TLR5 and TLR7/8 ligands on human T cells, and highlight an innate arm in T cell functions. They also suggest that some components from invading microorganisms may directly stimulate effector memory T cells located in tissues by up-regulating cytokine and chemokine production. |
Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionDisclosuresReferences |
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TLRs expressed by vertebrates are type 1 transmembrane proteins bearing an intracellular Toll/IL-1R homology domain (8). To date, 10 members of the TLR family that differ in ligand specificities and expression patterns have been described in humans. Among them, TLR2 is crucial for the recognition of a variety of bacterial PAMPs, including lipoproteins and peptidoglycans (9, 10), TLR3 is associated to the recognition of virus dsRNA (11), TLR4 is activated by LPS (12), TLR5 detects bacterial flagellin (13), TLR7 and TLR8 recognize imidazoquinolines (14, 15) and single-stranded viral RNA (16, 17) while TLR9 is required for response to unmethylated CpG DNA (18). The specificities can be extended by the ability of TLRs to heterodimerize and to interact with different adapter and accessory molecules (19). Binding of PAMPs to most of the TLRs initiates a signaling cascade that leads to the nuclear translocation of NF-
B members (20), resulting in the up-regulation of proinflammatory cytokines, reactive oxygen intermediates, and costimulatory molecule expression. TLR expression has been reported in several cell types including myeloid cells, neutrophils, and epithelial cells (6, 7). Although some innate cells (i.e., macrophages and neutrophils) activated via TLRs differentiate into effector cells that kill infectious agents, others, such as dendritic cells, activate T cells and thereby initiate adaptive immune response (21, 22, 23, 24, 25).
Previous studies reported that human T lymphocytes express TLR mRNA (26, 27), suggesting that TLR agonists may directly influence T cell effector function. Accordingly, TLR2 has been reported to be functional in T cells (28). In this study, we evaluated the functions of TLR5 and TLR7/8 expressed by highly purified human CD4+ T cells using their ligands flagellin and R-848, respectively. Flagellin, the major component of bacteria flagella, induces cytokine production by epithelial cells, monocytes, and NK cells (13, 29, 30). R-848 is a low m.w. immune response modifier of the imidazoquinoline family, with potent anti-viral and anti-tumor properties (31) elicited through TLR7 and TLR8 (14, 15). In this study, we report that flagellin and R-848 act directly, and in synergy with TCR-dependent and -independent stimuli, in inducing proliferation and cytokine production by human CD4+ T cells. Furthermore, we demonstrate that effector memory T cells, a subpopulation of memory T cells that confer immediate protection in peripheral tissues (32, 33), show enhanced responsiveness to APC-independent TLR activation. These data suggest a new role for TLRs in the activation of adaptive immune cells, and the participation of effector memory T cells in innate immunity.
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionDisclosuresReferences |
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PBMC were isolated from healthy volunteers by standard density gradient centrifugation on Ficoll-Paque (Amersham Pharmacia Biotech). CD4+ T cells were purified by negative selection using MACS technology according to the manufacturer’s instructions (Miltenyi Biotec), followed by FACS using PE-Cy7-labeled anti-CD3 mAb and allophycocyanin-labeled anti-CD4 mAb (both from BD Biosciences). FACS sorting was performed using a FACSAria cytofluorometer (BD Biosciences). The absence of contaminating monocytes, B cells, NK cells, and dendritic cells was controlled using anti-CD14, anti-CD19, anti-CD56 (BD Biosciences), anti-blood dendritic cell Ag (BDCA)-1, and anti-BDCA-2 (both from Miltenyi Biotec) mAbs, respectively. In other experiments, peripheral blood CD4+ T cells were separated into CD45RA+ and CD45RO+ cells by FACS sorting using allophycocyanin-labeled anti-CD4 mAb, PE-labeled anti-CD45RA mAb, and FITC-labeled anti-CD45RO mAb (all from BD Biosciences). CD4+CD45RO+ T cells were separated into CCR7+ and CCR7– cells by FACS sorting using FITC-labeled anti-CD45RO mAb and PE-labeled anti-CCR7 mAb (R&D Systems). Purity of the cells was >99.9%.
Cells were cultured in RPMI 1640 medium (Biowhittaker Cambrex) supplemented with 10% FCS (Biowest), 2 mM L-glutamine, 1 mM sodium pyruvate, 0.1 mM nonessential amino acids, 10 mM HEPES, 100 U/ml penicillin, and 100 µg/ml streptomycin (all from BioWhittaker Cambrex) at 37°C in 5% CO2. Cells (1 x 106 cells/ml) were cultured for 48 h in 48-well plates in the presence or the absence of 20 or 100 U/ml IL-2 (R&D Systems), 2 µg/ml anti-CD2 paired mAbs (clones T11/1 and T11.2/1; Pelicluster), 2 µg/ml anti-CD3 mAb (clone OKT3, American Type Culture Collection; without or with 5 µg/ml anti-CD28 mAb, clone CD28.2, BD Biosciences), 0.8–20 µg/ml poly(I:C) (Sigma-Aldrich), 0.4–10 µg/ml flagellin (from Salmonella typhimurium) or LPS (from 0111:B4 Escherichia coli strain), 0.1–5 µg/ml R-848 or Pam3CSK4 (all from InvivoGen), 0.5 µg/ml PHA (Murex Biotech) or a combination of these reagents as indicated.
RT-PCR analysis
TLR1 to TLR10 expression was analyzed by RT-PCR on FACS-sorted T cells. Briefly, total cytoplasmic RNA was extracted using TRIzol (Invitrogen Life Technologies), treated with RNase-free DNase (Promega), and reverse transcribed using the Superscript II RNase H-Reverse Transcriptase (Invitrogen Life Technologies) following the manufacturer’s recommendations. PCR amplification was performed with an amount of cDNA corresponding to 50 ng of starting total RNA (5 min at 94°C followed by 30 cycles (30 s at 94°C, 30 s at 55°C, and 1 min at 72°C) followed by a final extension of 7 min at 72°C). The primer sequences used for PCR are: hTLR1, sense 5'-CGT AAA ACT GGA AGC TTT GCA AGA-3', antisense 5'-CCT TGG GCC ATT CCA AAT AAG TCC-3'; hTLR2, sense 5'-GGC CAG CAA ATT ACC TGT GTG-3', antisense 5'-CCA GGT AGC TCT TGG TGT TCA-3'; hTLR3, sense 5'-ATT GGG TCT GGG AAC ATT TCT CTT C-3', antisense 5'-GTG AGA TTT AAA CAT TCT TCG C-3'; hTLR4, sense 5'-CTG CAA TGG ATC AAG GAC CA-3', antisense 5'-TCC CAC TCC AGG TAA GTG TT-3'; hTLR5, sense 5'-CAT TGT ATG CAC TGT CAC TC-3', antisense 5'-CCA CCA CCA TGA TGA GAG CA-3'; hTLR6, sense 5'-TAG GTC TCA TGA CGA AGG AT-3', antisense 5'-GGC CAC TGC AAA TAA CTC CG-3'; hTLR7, sense 5'-AGT GTC TAA AGA ACC TGG-3', antisense 5'-CTT GGC CTT ACA GAA ATG-3'; hTLR8, sense 5'-CAG ATT AGC AGG CGT AAC ACA TCA-3', antisense 5'-AAT GTC ACA GGT GCA TTC AAA GGG-3'; hTLR9, sense 5'-TTA TGG ACT TCC TGC TGG TGG AGG TGC-3', antisense 5'-CTG CGT TTT GTC GAA GAC CA-3'; hTLR10, sense 5'-GCT AGT TCT GGG GTT GGC TGT GGC-3', antisense 5'-CAT TAA TAG CAG CTC GAA GGT TTG CC-3'; GAPDH, sense 5'-GGA GGT GGA GGT CGG AGT C-3', antisense 5'-GAA GAT GGT GAT GGG ATT TTC-3'. RNA integrity and cDNA synthesis was verified by amplifying GAPDH cDNA. Amplified fragments were size-separated by electrophoresis and visualized by ethidium bromide.
Cytokine quantification
Cells were incubated for 48 h with various stimuli, and the concentrations of IFN-, IL-2, IL-4, IL-8, and IL-10 were measured in cell-free culture supernatants by ELISA, according to the manufacturer’s recommendations. Specific capture and detection Abs for IFN- were from Mabtech (sensitivity of 5 pg/ml) and those for IL-2, IL-8, and IL-10 were from R&D Systems (sensitivity of 50, 15, and 10 pg/ml, respectively). IL-4 was quantified using a commercial kit (R&D Systems; sensitivity of 0.13 pg/ml).
Proliferation assays
Cells (4.105/ml) were seeded in triplicate in 96-well flat-bottom plates and stimulated as described above for 72 h. Cells were pulsed during the last 16 h with 0.25 µCi/well [3H]thymidine (Amersham Pharmacia Biotech). Radioactive incorporation was measured by standard liquid scintillation counting, and results expressed in proliferation index (mean of triplicate values) were defined as follows: A/B, were A and B are the cpm values obtained in the presence or absence of TLR ligand, respectively.
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Results |
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We evaluated whether human CD4+ T cells express mRNA encoding TLRs. Results showed that highly purified CD4+ T cells expressed TLR1–5 (26, 27). TLR7 and TLR9 mRNA were also expressed, although at a lower level. TLR6, 8, and 10 mRNA expression was weak or undetectable (Fig. 1A, upper panel). Moreover, the levels of TLR mRNA varied from donor to donor (data not shown).
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Together, these data showed that freshly isolated human CD4+ T cells express mRNA encoding TLRs.
Ligands for TLR2, 5, 7, and 8 up-regulate IFN- production by human CD4+ T cells
Therefore, we analyzed the effect of Pam3CSK4, poly(I:C), LPS, flagellin, and R-848, ligands for TLR2, TLR3, TLR4, TLR5, and TLR7/8, respectively, on IFN- production by T cells.
Pam3CSK4, flagellin, and R-848 induced a limited production of IFN- (<2 ng/ml) but synergized with suboptimal concentrations of anti-CD3 mAb, anti-CD2 mAbs, or IL-2 in inducing IFN- production by T cells from six healthy subjects (Fig. 2A). According to the subject tested, variations in the levels of IFN- produced in response to one of the TLR ligands and in the intensity of T cell response to each of the ligands were observed (Fig. 2A). As an example, in the presence of the anti-CD2 mAbs, increase in IFN- production varied from 2.6- to 24.5-fold in response to Pam3CSK4, from 1.9- to 18.5-fold in response to flagellin, and from 3.1- to 36.7-fold in response to R-848 for the six subjects tested. Accordingly, Fig. 2 shows representative data obtained with two of six subjects. The effects of Pam3CSK4, flagellin, and R-848 on IFN- production were dose dependent and maximal at concentrations of 1, 5, and 1 µg/ml, respectively (Fig. 2B). These concentrations were used throughout the study. TLR ligands-enhanced IFN- production by activated T cells was time dependent (Fig. 2C). In the presence of immobilized anti-CD3 mAb, the effect of Pam3CSK4, flagellin, or R-848 was significant after 16 h of stimulation and maximal at day 3. Although the levels of IFN- induced by an anti-CD28 mAb (used as a control of the maximum IFN- secretion capacity of T cells) were higher, kinetics of IFN- production in the presence of TLR ligands were similar to those obtained in the presence of the anti-CD28 mAb (Fig. 2C).
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production by CD4+ T cells (data not shown). Finally, at any concentrations tested, and even in the presence of the additional stimuli, anti-CD3 mAb, anti-CD2 mAbs, or IL-2, poly(I:C), and LPS did not affect IFN- production (Fig. 2B). Together, these data reinforce results from others showing that TLR2 is functional in human T cells (28) and demonstrate, for the first time, a functional role for TLR5 and TLR7/8 ligands in stimulating human T cells. TLR ligands up-regulate T cell proliferation and IL-2 and IL-10 production, but differentially affect IL-8 production
We next analyzed more precisely the nature of the T cell response to TLR 2, 5, and 7/8 ligands. Used alone, Pam3CSK4, flagellin, and R-848 had a limited effect on T cell proliferation (Fig. 3) and failed to modulate IL-2 and IL-10 production (data not shown). However, they synergized with anti-CD3 mAb, anti-CD2 mAbs, or IL-2 in up-regulating T cell proliferation (Fig. 3) and IL-2 and IL-10 production (Fig. 4A). In parallel, IL-4 production was observed in response to anti-CD3 plus anti-CD28 mAbs (used as a positive control), but remained undetectable after treatment with TLR ligands alone or in combination with anti-CD3 mAb, anti-CD2 mAbs, or IL-2 (data not shown).
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Effector memory CCR7–CD45RO+ T cells are highly sensitive to TLR ligands
We then compared naive vs memory T cell sensitivity to Pam3CSK4, flagellin, and R-848. Highly purified CD4+ T cells were separated into CD45RA+ (naive) and CD45RO+ (memory) T cells and incubated with TLR ligands in the absence or presence of anti-CD2 mAbs, IL-2 (Fig. 5), or anti-CD3 mAb (data not shown). Whatever the costimulus used, TLR ligands up-regulated IFN- production (Fig. 5A) and T cell proliferation (Fig. 5B) more efficiently in memory than in naive T cells. Representative results obtained with two of six subjects are presented. These data showed that memory CD4+ T cells are more sensitive to TLR ligands than naive T cells.
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in response to TLRs than central memory T cells (Fig. 6). As an example, in response to anti-CD2 mAbs, increase in IFN- production in CCR7– compared with CCR7+ cells varied from 1.9- to 3.8-fold in response to Pam3CSK4, from 1.7- to 2.9-fold in response to flagellin, and from 1.9- to 3.5-fold in response to R-848, for the five subjects tested. As a positive control, effector memory CD4+ T cells stimulated by anti-CD3 plus anti-CD28 mAbs produced higher levels of IFN- than central memory T cells (32).
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionDisclosuresReferences |
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Previous studies reported that human peripheral blood T cells express TLR mRNA (26, 27). This study aimed to evaluate whether TLRs may have a functional role in T lymphocytes. As most of the hemopoietic cells express TLRs and respond to TLR ligands (7), the use of highly purified T cells was a prerequisite. CD4+ T cells were purified from peripheral blood by a two-step purification protocol combining immunomagnetic and FACS sorting. Following this protocol, no contaminating B cells, NK cells (that produce IFN- and proliferate in response to TLR2 and TLR5 ligands; Ref. 30), and APCs (such as monocytes and myeloid or plasmacytoid dendritic cells) that are highly sensitive to TLR-mediated activation, were phenotypically and functionally detected in our purified T cells. This data was reinforced by the observation that poly(I:C), a TLR3 ligand that induces IL-8 production by monocytes (G. Caron and P. Jeannin, unpublished data), did not induce IL-8 production by purified CD4+ T cells.
In agreement with previous studies (26, 27), we observed that human CD4+ T cells express mRNA encoding most of the members of the TLR family, except TLR10 (26). Ligands for TLR2 (Pam3CSK4), TLR5 (flagellin), and TLR7/8 (R-848) up-regulate proliferation and IL-2, IL-8, IL-10, and IFN- production by human CD4+ T cells, in the absence of APCs. These data are, to our knowledge, the first demonstration that human T cells are sensitive to TLR5 and TLR7/8 ligands. We also reinforce recent data showing that bacterial lipopeptide (Pam3CSK4) costimulates human CD4+ T cell proliferation and IFN- production (28).
Flagellin and R-848 induce the production of cytokines by CD4+ T cells. Flagellin is a bacterial component that is highly immunogenic in the absence of adjuvant (35), a property related to its ability to stimulate dendritic cells (36). In the absence of adjuvant, flagellin favors in vivo the development of a Th2-polarized response (37). Flagellin did not induce IL-4 or CCL17 (thymus and activation-regulated chemokine) and CCL22 (macrophage-derived chemokine) production (data not shown), two chemokines produced by activated T cells that favor the recruitment of Th2 cells (38, 39). These results suggest that the ability of flagellin to favor the induction of Th2 responses in vivo may involve cell types other than T cells, such as dendritic cells. In agreement with this hypothesis, and as previously reported by others, we observed that, in contrast to IFN- used as a positive control (40), flagellin did not affect LPS-induced IL-12 p70 production by human monocyte-derived dendritic cells (P. Jeannin, unpublished data). Recent studies reported that viral ssRNA activate innate cells via TLR7 (16, 17). Resiquimod (R-848) belongs to the imidazoquinoline family and exhibits potent antitumor and antiviral activities (31). Imidazoquinolines induce the production of IL-12, IFN-
, and IFN- by murine and human mononuclear cells and, in contrast to flagellin, favor the development of Th1-polarized responses (41). R-848 is a synthetic agonist for TLR7 and TLR8 and is easily usable in in vitro assays. In the presence of APCs, R-848 shifts human allergen-specific CD4+ Th2 lymphocytes into IFN--producing cells (42). Our study shows a direct effect of R-848 on IFN- production by human T cells with no induction of IL-4 or Th2-attracting chemokines (data not shown). These data show that ssRNA, released during virus-infected cell lysis, can induce the production of IFN- that, in turn, exhibits direct antiviral properties (43).
An activation of T lymphocytes by PAMPs should occur upon epithelial cell barrier disruption. As a consequence, PAMP-activated T cells may produce cytokines involved in the recruitment and activation of inflammatory cells to initiate appropriate immune responses. IL-8 is involved in the recruitment of inflammatory cells and IFN- plays a critical role in the activation of epithelial cells. At the opposite, the immunomodulatory cytokine IL-10 controls the outcome of the immune response and maintains tissue homeostasis. Surprisingly, we observed that R-848, in contrast to flagellin and Pam3CSK4, decreased in a dose-dependent manner anti-CD2 mAbs-induced IL-8 production. This effect appears restricted to IL-8 production as R-848 potentiates the anti-CD2 mAbs-induced IL-2, IL-10, and IFN- synthesis. This result suggests that signaling pathways associated to TLR2, TLR5, and TLR7/8 may differ (44), and additional experiments are required to explain this observation.
Flagellin and Pam3CSK4 induced proliferation of human CD4+ T lymphocytes. The in vivo relevance of this result remains unclear. Recently, Tulic et al. (45) reported that ex vivo LPS application in nasal mucosa induced the proliferation of T lymphocytes. Whether the induction of proliferation was direct or not remains unclear. Nevertheless, this study shows that proliferation of T lymphocytes localized within tissues can be initiated by TLR agonists.
TLR ligands have a limited T cell stimulatory activity when used alone (except on IL-8 production) but synergized with TCR-dependent and -independent stimuli. This result is in accordance with data showing that myeloid cells are more sensitive to PAMP-mediated activation than T cells and suggests 1) that T cells require a strong PAMP-mediated activation signal to be efficiently stimulated, and 2) that an activation of T cells by PAMPs may occur during a massive entry of microorganisms.
Although human T cells express TLR3 and TLR4 mRNA, we failed in detecting an effect of their ligands (poly (I:C) and LPS, respectively) on proliferation and cytokine production by T cells. Recent studies reported that murine regulatory CD4+CD25+ T cells respond to LPS (46), and that dsRNA directly enhances activated CD4+ T cell survival (47). However, in accordance with our data, Komai-Koma et al. (28) also failed to detect an effect of LPS or poly(I:C) on human CD4+ T cells. The absence of effect of these ligands may be related to 1) the absence of accessory molecules on T cells, such as CD14 that belongs to the LPS-receptor complex, 2) the intracellular localization of the TLR proteins that can be modified upon activation, as previously reported for TLR5 (48) or, 3) the absence of TLR proteins. Additional experiments are required to investigate these hypotheses.
We observed that memory CD4+ T cells are more sensitive to TLR-mediated activation than naive CD4+ T cells. This result could be attributed to the fact that memory T cells, which have already encountered the Ag, require less stringent stimulatory signals than naive T cells to be activated (49). The observation that effector memory CD4+ T cells are also more sensitive than central memory CD4+ T cells reinforces this hypothesis (32, 33). Immune memory is displayed by central and effector memory T cells that exhibit distinct phenotypic and biologic characteristics (33). Central memory T cells, which mediate reactive memory, express CCR7, home to the T cell areas of secondary lymphoid organs and have little effector function. They readily proliferate and differentiate into effector cells in response to an antigenic stimulation. Effector memory T cells support protective memory. They lack CCR7 expression and then migrate to inflamed peripheral tissues where they display immediate effector function. Our results also underline that T cells that have already encountered Ags are more sensitive to TCR-independent TLR-mediated stimulation. Based on these observations, it is tempting to speculate that the pool of Ag-primed T cells, which enter peripheral tissues to mediate inflammatory reaction, could be efficiently stimulated by PAMPs and contribute to contain invasive pathogens through the production of cytokines such as IL-8 and IFN- that favor phagocyte recruitment and activation, respectively. Finally, the observation that both memory T cell subsets respond to TLR ligands suggest that stimulation with PAMPs may contribute to the maintenance of a local polyclonal repertoire of memory T cells.
Although it has been recently suggested that TLR2 could be unique in its ability to costimulate T cell functions, in this study, we demonstrate that TLR5 and TLR7/8 ligands act synergistically with TCR-dependent and TCR-independent stimuli to up-regulate cytokine production and proliferation of human T cells with an optimal effect on memory T cells. This mechanism may participate in local memory T cell homeostasis and contribute, together with costimulatory signals such as IL-2 or CD58, to stimulation of effector T cells recruited at the site of microorganism entry.
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Disclosures |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionDisclosuresReferences |
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Footnotes |
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1 This work was supported by Action Concertée Incitative Microbiologie, Fonds National de la Science 2003. D.D. was supported by La Ligue Contre le Cancer, Comité Départemental de Maine et Loire. G. C. was supported by Conseil Général du Maine er Loire and Angers Agglomération Développement. 
2 Address correspondence and reprint requests to Dr. Yves Delneste, Institut National de la Santé et de la Recherche Médicale Unité 564, University Hospital of Angers, 4, rue Larrey, F-49933 Angers, France. E-mail address: yves.delneste{at}univ-angers.fr
3 Abbreviation used in this paper: PAMP, pathogen-associated molecular pattern; BDCA, blood dendritic cell antigen.
Received for publication September 22, 2004. Accepted for publication May 16, 2005.
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References |
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B by Toll-like receptor 3. Nature 413: 732-738.[Medline]
B degradation, induction of nitric oxide synthase, induction of proinflammatory mediators, and cardiovascular dysfunction. J. Immunol. 166: 1248-1260.-defensin production. Blood 104: 1778-1783.-producing cells. J. Allergy Clin. Immunol. 111: 380-388.[Medline]
. Annu. Rev. Immunol. 15: 749-795.[Medline]
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C.-L. Ku, H. von Bernuth, C. Picard, S.-Y. Zhang, H.-H. Chang, K. Yang, M. Chrabieh, A. C. Issekutz, C. K. Cunningham, J. Gallin, et al. Selective predisposition to bacterial infections in IRAK-4 deficient children: IRAK-4 dependent TLRs are otherwise redundant in protective immunity J. Exp. Med., October 1, 2007; 204(10): 2407 - 2422. [Abstract] [Full Text] [PDF]
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S. Thibault, M. R. Tardif, C. Barat, and M. J. Tremblay TLR2 Signaling Renders Quiescent Naive and Memory CD4+ T Cells More Susceptible to Productive Infection with X4 and R5 HIV-Type 1 J. Immunol., October 1, 2007; 179(7): 4357 - 4366. [Abstract] [Full Text] [PDF]
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C. Mazzon, B. Baldani-Guerra, P. Cecchini, T. Kasic, A. Viola, M. de Bernard, B. Arico, F. Gerosa, and E. Papini IFN-{gamma} and R-848 Dependent Activation of Human Monocyte-Derived Dendritic Cells by Neisseria meningitidis Adhesin A J. Immunol., September 15, 2007; 179(6): 3904 - 3916. [Abstract] [Full Text] [PDF]
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M.-R. Sarrias, M. Farnos, R. Mota, F. Sanchez-Barbero, A. Ibanez, I. Gimferrer, J. Vera, R. Fenutria, C. Casals, J. Yelamos, et al. CD6 binds to pathogen-associated molecular patterns and protects from LPS-induced septic shock PNAS, July 10, 2007; 104(28): 11724 - 11729. [Abstract] [Full Text] [PDF]
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T. Imanishi, H. Hara, S. Suzuki, N. Suzuki, S. Akira, and T. Saito Cutting Edge: TLR2 Directly Triggers Th1 Effector Functions J. Immunol., June 1, 2007; 178(11): 6715 - 6719. [Abstract] [Full Text] [PDF]
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N. Foster, S. R. Lea, P. M. Preshaw, and J. J. Taylor Pivotal Advance: Vasoactive intestinal peptide inhibits up-regulation of human monocyte TLR2 and TLR4 by LPS and differentiation of monocytes to macrophages J. Leukoc. Biol., April 1, 2007; 81(4): 893 - 903. [Abstract] [Full Text] [PDF]
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M. R. Goldberg, N. Luknar-Gabor, G. Zadik-Mnuhin, P. Koch, J. Tovbin, and Y. Katz Synergy between LPS and immobilized anti-human CD3{epsilon} mAb for activation of cord blood CD3+ T cells Int. Immunol., January 1, 2007; 19(1): 99 - 103. [Abstract] [Full Text] [PDF]
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J. Tabiasco, E. Devevre, N. Rufer, B. Salaun, J.-C. Cerottini, D. Speiser, and P. Romero Human Effector CD8+ T Lymphocytes Express TLR3 as a Functional Coreceptor J. Immunol., December 15, 2006; 177(12): 8708 - 8713. [Abstract] [Full Text] [PDF]
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J. A. Deane and S. Bolland Nucleic Acid-Sensing TLRs as Modifiers of Autoimmunity J. Immunol., November 15, 2006; 177(10): 6573 - 6578. [Abstract] [Full Text] [PDF]
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J. P. Wang, P. Liu, E. Latz, D. T. Golenbock, R. W. Finberg, and D. H. Libraty Flavivirus Activation of Plasmacytoid Dendritic Cells Delineates Key Elements of TLR7 Signaling beyond Endosomal Recognition J. Immunol., November 15, 2006; 177(10): 7114 - 7121. [Abstract] [Full Text] [PDF]
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P. Lewkowicz, N. Lewkowicz, A. Sasiak, and H. Tchorzewski Lipopolysaccharide-Activated CD4+CD25+ T Regulatory Cells Inhibit Neutrophil Function and Promote Their Apoptosis and Death J. Immunol., November 15, 2006; 177(10): 7155 - 7163. [Abstract] [Full Text] [PDF]
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R. Chakraverty, D. Cote, J. Buchli, P. Cotter, R. Hsu, G. Zhao, T. Sachs, C. M. Pitsillides, R. Bronson, T. Means, et al. An inflammatory checkpoint regulates recruitment of graft-versus-host reactive T cells to peripheral tissues J. Exp. Med., August 7, 2006; 203(8): 2021 - 2031. [Abstract] [Full Text] [PDF]
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S. Babu, C. P. Blauvelt, V. Kumaraswami, and T. B. Nutman Cutting Edge: Diminished T Cell TLR Expression and Function Modulates the Immune Response in Human Filarial Infection J. Immunol., April 1, 2006; 176(7): 3885 - 3889. [Abstract] [Full Text] [PDF]
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D. Wesch, S. Beetz, H.-H. Oberg, M. Marget, K. Krengel, and D. Kabelitz Direct Costimulatory Effect of TLR3 Ligand Poly(I:C) on Human {gamma}{delta} T Lymphocytes J. Immunol., February 1, 2006; 176(3): 1348 - 1354. [Abstract] [Full Text] [PDF]
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N. K. Crellin, R. V. Garcia, O. Hadisfar, S. E. Allan, T. S. Steiner, and M. K. Levings Human CD4+ T Cells Express TLR5 and Its Ligand Flagellin Enhances the Suppressive Capacity and Expression of FOXP3 in CD4+CD25+ T Regulatory Cells J. Immunol., December 15, 2005; 175(12): 8051 - 8059. [Abstract] [Full Text] [PDF]
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) and FACS-sorted (
) cells were cultured at 106 cells/ml for 3 days in the presence of 0.5 µg/ml PHA or 10 µg/ml anti-CD3 plus 5 µg/ml anti-CD28 mAbs. Proliferation was measured by [3H]thymidine incorporation, and results are expressed in cpm. A–C, Results are representative of data obtained with T cells from one of five healthy donors.
) were purified from CD4+ T cells by FACS sorting and either unstimulated or stimulated with IL-2 (100 U/ml for cytokine production or 20 U/ml for proliferation assay) or anti-CD2 mAbs (2 µg/ml) in the absence or presence of 1 µg/ml Pam3CSK4, 5 µg/ml flagellin, or 1 µg/ml R-848. IFN-