scholarly journals Importance of the N-Distal AP-2 Binding Element in Nef for Simian Immunodeficiency Virus Replication and Pathogenicity in Rhesus Macaques

2006 ◽  
Vol 80 (9) ◽  
pp. 4469-4481 ◽  
Author(s):  
Matthias Brenner ◽  
Jan Münch ◽  
Michael Schindler ◽  
Steffen Wildum ◽  
Nicole Stolte ◽  
...  
Keyword(s):  
Viral Replication ◽  
Rhesus Macaques ◽  
Point Mutations ◽  
Mhc I ◽  
Viral Loads ◽  
Mhc Ii ◽  
Histocompatibility Complex ◽  
Immunodeficiency Virus ◽  
Clathrin Adaptor

ABSTRACT Point mutations in SIVmac239 Nef disrupting CD4 downmodulation and enhancement of virion infectivity attenuate viral replication in acutely infected rhesus macaques, but changes selected later in infection fully restore Nef function (A. J. Iafrate et al., J. Virol. 74:9836-9844, 2000). To further evaluate the relevance of these Nef functions for viral persistence and disease progression, we analyzed an SIVmac239 Nef mutant containing a deletion of amino acids Q64 to N67 (Δ64-67Nef). This mutation inactivates the N-distal AP-2 clathrin adaptor binding element and disrupts the abilities of Nef to downregulate CD4, CD28 and CXCR4 and to stimulate viral replication in vitro. However, it does not impair the downmodulation of CD3 and class I major histocompatibility complex (MHC-I) or MHC-II and the upregulation of the MHC-II-associated invariant chain, and it has only a moderate effect on the enhancement of virion infectivity. Replication of the Δ64-67Nef variant in acutely infected macaques was intermediate between grossly nef-deleted and wild-type SIVmac239. Subsequently, three of six macaques developed moderate to high viral loads and developed disease, whereas the remaining animals efficiently controlled SIV replication and showed a more attenuated clinical course of infection. Sequence analysis revealed that the deletion in nef was not repaired in any of these animals. However, some changes that slightly enhanced the ability of Nef to downmodulate CD4 and moderately increased Nef-mediated enhancement of viral replication and infectivity in vitro were observed in macaques developing high viral loads. Our results imply that both the Nef functions that were disrupted by the Δ64-67 mutation and the activities that remained intact contribute to viral pathogenicity.

scholarly journals The Major Histocompatibility Complex Class II Alleles Mamu-DRB1*1003 and -DRB1*0306 Are Enriched in a Cohort of Simian Immunodeficiency Virus-Infected Rhesus Macaque Elite Controllers

2007 ◽  
Vol 82 (2) ◽  
pp. 859-870 ◽  
Author(s):  
Juan P. Giraldo-Vela ◽  
Richard Rudersdorf ◽  
Chungwon Chung ◽  
Ying Qi ◽  
Lyle T. Wallace ◽  
...  
Keyword(s):  
Major Histocompatibility Complex ◽  
T Cell ◽  
Viral Replication ◽  
Rhesus Macaques ◽  
Complex Class ◽  
Elite Controllers ◽  
Mhc Ii ◽  
Histocompatibility Complex ◽  
Immunodeficiency Virus

ABSTRACT The role of CD4+ T cells in the control of human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) replication is not well understood. Even though strong HIV- and SIV-specific CD4+ T-cell responses have been detected in individuals that control viral replication, major histocompatibility complex class II (MHC-II) molecules have not been definitively linked with slow disease progression. In a cohort of 196 SIVmac239-infected Indian rhesus macaques, a group of macaques controlled viral replication to less than 1,000 viral RNA copies/ml. These elite controllers (ECs) mounted a broad SIV-specific CD4+ T-cell response. Here, we describe five macaque MHC-II alleles (Mamu-DRB*w606, -DRB*w2104, -DRB1*0306, -DRB1*1003, and -DPB1*06) that restricted six SIV-specific CD4+ T-cell epitopes in ECs and report the first association between specific MHC-II alleles and elite control. Interestingly, the macaque MHC-II alleles, Mamu-DRB1*1003 and -DRB1*0306, were enriched in this EC group (P values of 0.02 and 0.05, respectively). Additionally, Mamu-B*17-positive SIV-infected rhesus macaques that also expressed these two MHC-II alleles had significantly lower viral loads than Mamu-B*17-positive animals that did not express Mamu-DRB1*1003 and -DRB1*0306 (P value of <0.0001). The study of MHC-II alleles in macaques that control viral replication could improve our understanding of the role of CD4+ T cells in suppressing HIV/SIV replication and further our understanding of HIV vaccine design.

scholarly journals Comprehensive Analysis of Nef Functions Selected in Simian Immunodeficiency Virus-Infected Macaques

2004 ◽  
Vol 78 (19) ◽  
pp. 10588-10597 ◽  
Author(s):  
Michael Schindler ◽  
Jan Münch ◽  
Matthias Brenner ◽  
Christiane Stahl-Hennig ◽  
Jacek Skowronski ◽  
...  
Keyword(s):  
Simian Immunodeficiency Virus ◽  
Rhesus Macaques ◽  
Surface Expression ◽  
Viral Fitness ◽  
Cell Surface Expression ◽  
Mhc I ◽  
Mhc Ii ◽  
Immunodeficiency Virus

ABSTRACT A variety of simian immunodeficiency virus (SIVmac) nef mutants have been investigated to clarify which in vitro Nef functions contribute to efficient viral replication and pathogenicity in rhesus macaques. Most of these nef alleles, however, were only functionally characterized for their ability to down-modulate CD4 and class I major histocompatibility complex (MHC-I) cell surface expression and to enhance SIV replication and infectivity. To obtain information on the in vivo relevance of more recently established Nef functions, we examined the ability of a large panel of constructed SIVmac Nef mutants and of variants that emerged in infected macaques to down-regulate CD3, CD28, and MHC-II and to up-regulate the MHC-II-associated invariant chain (Ii). We found that all these four Nef functions were restored in SIV-infected macaques. In most cases, however, the initial mutations and the changes selected in vivo affected several in vitro Nef functions. For example, truncated Nef proteins that emerged in animals infected with SIVmac239 containing a 152-bp deletion in nef efficiently modulated both CD3 and Ii surface expression. Overall, our results suggest that the effect of Nef on each of the six cellular receptors investigated contributes to viral fitness in the infected host but also indicate that modulation of CD3, MHC-I, MHC-II, or Ii surface expression alone is insufficient for SIV virulence.

scholarly journals Effect of the Attenuating Deletion and of Sequence Alterations Evolving In Vivo on Simian Immunodeficiency Virus C8-Nef Function

1999 ◽  
Vol 73 (4) ◽  
pp. 2790-2797 ◽  
Author(s):  
Silke Carl ◽  
A. John Iafrate ◽  
Jacek Skowronski ◽  
Christiane Stahl-Hennig ◽  
Frank Kirchhoff
Keyword(s):  
Viral Replication ◽  
Simian Immunodeficiency Virus ◽  
Point Mutations ◽  
Residual Activity ◽  
Intermediate Phenotype ◽  
Cell Surface Expression ◽  
In Vitro Assays ◽  
Immunodeficiency Virus

ABSTRACT The simian immunodeficiency virus macC8 (SIVmacC8) variant has been used in a European Community Concerted Action project to study the efficacy and safety of live attenuated SIV vaccines in a large number of macaques. The attenuating deletion in the SIVmacC8nef-long terminal repeat region encompasses only 12 bp and is “repaired” in a subset of infected animals. It is unknown whether C8-Nef retains some activity. Since it seems important to use only well-characterized deletion mutants in live attenuated vaccine studies, we analyzed the relevance of the deletion, and the duplications and point mutations selected in infected macaques for Nef function in vitro. The deletion, affecting amino acids 143 to 146 (DMYL), resulted in a dramatic decrease in Nef stability and function. The initial 12-bp duplication resulted in efficient Nef expression and an intermediate phenotype in infectivity assays, but it did not significantly restore the ability of Nef to stimulate viral replication and to downmodulate CD4 and class I major histocompatibility complex cell surface expression. The additional substitutions however, which subsequently evolved in vivo, gradually restored these Nef functions. It was noteworthy that coinfection experiments in the T-lymphoid 221 cell line revealed that even SIVmac nef variants carrying the original 12-bp deletion readily outgrew an otherwise isogenic virus containing a 182-bp deletion in the nef gene. Thus, although C8-Nef is unstable and severely impaired in in vitro assays, it maintains some residual activity to stimulate viral replication.

scholarly journals Immunization with recombinant macaque major histocompatibility complex class I and II and human immunodeficiency virus gp140 inhibits simian–human immunodeficiency virus infection in macaques

2012 ◽  
Vol 93 (7) ◽  
pp. 1506-1518 ◽  
Author(s):  
Gui-Bo Yang ◽  
Yufei Wang ◽  
Kaboutar Babaahmady ◽  
Jørgen Schøller ◽  
Durdana Rahman ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Major Histocompatibility Complex ◽  
Rhesus Macaques ◽  
Class I ◽  
Major Histocompatibility ◽  
Viral Loads ◽  
Histocompatibility Complex ◽  
Immunodeficiency Virus ◽  
Peak Viral Load ◽  
Hiv Gp120

Genetic, epidemiological and experimental evidence suggest that the major histocompatibility complex (MHC) is critical in controlling human immunodeficiency virus (HIV) infection. The objectives of this study were to determine whether novel recombinant Mamu MHC constructs would elicit protection against rectal challenge with heterologous simian–human immunodeficiency virus (SHIV) strain SF162.P4 in rhesus macaques. Mamu class I and II gene products were linked together with HIV gp140, simian immunodeficiency virus (SIV) p27 and heat-shock protein 70 to dextran. The vaccine was administered to two groups, each consisting of nine macaques, either subcutaneously (SC), or rectally and boosted by SC immunization. The controls were untreated or adjuvant-treated animals. Repetitive rectal challenges with up to ten doses of SHIV SF162.P4 showed a significant decrease in the peak and sequential viral RNA concentrations, and three macaques remained uninfected, in the nine SC-immunized animals, compared with infection in all nine controls. Macaques immunized rectally followed by SC boosters showed a less significant decrease in both sequential and peak viral loads compared with the SC-immunized animals, and all were infected following rectal challenge with SHIV SF162.P4. Plasma and mucosal IgG and IgA antibodies to Mamu class I alleles and HIV gp120, as well as to RANTES (regulated upon activation, normal T-cell expressed, and secreted; CCR5) were increased, and showed significant inverse correlations with the peak viral load. These results suggested that allo-immunization with recombinant MHC constructs linked to HIV–SIV antigens merits further investigation in preventing HIV-1 infection.

scholarly journals Simian Immunodeficiency Virus in Which nef and U3 Sequences Do Not Overlap Replicates Efficiently In Vitro and In Vivo in Rhesus Macaques

2001 ◽  
Vol 75 (17) ◽  
pp. 8137-8146 ◽  
Author(s):  
Jan Münch ◽  
Nadia Adam ◽  
Nathaly Finze ◽  
Nicole Stolte ◽  
Christiane Stahl-Hennig ◽  
...  
Keyword(s):  
Simian Immunodeficiency Virus ◽  
Rhesus Macaques ◽  
Point Mutations ◽  
Regulatory Elements ◽  
Coding Sequences ◽  
Reading Frame ◽  
Immunodeficiency Virus ◽  
Primate Lentiviruses

ABSTRACT The nef genes of human immunodeficiency virus and simian immunodeficiency virus (SIV) overlap about 80% of the U3 region of the 3′ long terminal repeat (LTR) and contain several essentialcis-acting elements (here referred to as the TPI region): a T-rich region, the polypurine tract, and attachment (att) sequences required for integration. We inactivated the TPI region in the nef reading frame of the pathogenic SIVmac239 clone (239wt) by 13 silent point mutations. To restore viral infectivity, intact cis-regulatory elements were inserted just downstream of the mutatednef gene. The resulting SIV genome contains U3 regions that are 384 bp shorter than the 517-bp 239wt U3 region. Overall, elimination of the duplicated Nef coding sequences truncates the proviral genome by 350 bp. Nonetheless, it contains all known coding sequences and cis-acting elements. The TPI mutant virus expressed functional Nef and replicated like 239wt in all cell culture assays and in vivo in rhesus macaques. Notably, these SIVmac constructs allow us to study Nef function in the context of replication-competent viruses without the restrictions of overlapping LTR sequences and important cis-acting elements. The genomes of all known primate lentiviruses contain a large overlap between nefand the U3 region. We demonstrate that this conserved genomic organization is not obligatory for efficient viral replication and pathogenicity.

scholarly journals The Frequency of Vaccine-Induced T-Cell Responses Does Not Predict the Rate of Acquisition after Repeated Intrarectal SIVmac239 Challenges inMamu-B*08+Rhesus Macaques

2018 ◽  
Vol 93 (5) ◽  
Author(s):  
Mauricio A. Martins ◽  
Lucas Gonzalez-Nieto ◽  
Young C. Shin ◽  
Aline Domingues ◽  
Martin J. Gutman ◽  
...  
Keyword(s):  
T Cell ◽  
Rhesus Macaques ◽  
T Cell Responses ◽  
Complex Class ◽  
Class I Mhc ◽  
Mhc I ◽  
Cell Responses ◽  
Histocompatibility Complex ◽  
Immunodeficiency Virus ◽  
Siv Infection

ABSTRACTApproximately 50% of rhesus macaques (RMs) expressing the major histocompatibility complex class I (MHC-I) alleleMamu-B*08spontaneously control chronic-phase viremia after infection with the pathogenic simian immunodeficiency virus mac239 (SIVmac239) clone. CD8+T-cell responses in these animals are focused on immunodominant Mamu-B*08-restricted SIV epitopes in Vif and Nef, and prophylactic vaccination with these epitopes increases the incidence of elite control in SIVmac239-infectedMamu-B*08-positive (Mamu-B*08+) RMs. Here we evaluated if robust vaccine-elicited CD8+T-cell responses against Vif and Nef can prevent systemic infection inMamu-B*08+RMs following mucosal SIV challenges. TenMamu-B*08+RMs were vaccinated with a heterologous prime/boost/boost regimen encoding Vif and Nef, while six sham-vaccinated MHC-I-matched RMs served as the controls for this experiment. Vaccine-induced CD8+T cells against Mamu-B*08-restricted SIV epitopes reached high frequencies in blood but were present at lower levels in lymph node and gut biopsy specimens. Following repeated intrarectal challenges with SIVmac239, all control RMs became infected by the sixth SIV exposure. By comparison, four vaccinees were still uninfected after six challenges, and three of them remained aviremic after 3 or 4 additional challenges. The rate of SIV acquisition in the vaccinees was numerically lower (albeit not statistically significantly) than that in the controls. However, peak viremia was significantly reduced in infected vaccinees compared to control animals. We found no T-cell markers that distinguished vaccinees that acquired SIV infection from those that did not. Additional studies will be needed to validate these findings and determine if cellular immunity can be harnessed to prevent the establishment of productive immunodeficiency virus infection.IMPORTANCEIt is generally accepted that the antiviral effects of vaccine-induced classical CD8+T-cell responses against human immunodeficiency virus (HIV) are limited to partial reductions in viremia after the establishment of productive infection. Here we show that rhesus macaques (RMs) vaccinated with Vif and Nef acquired simian immunodeficiency virus (SIV) infection at a lower (albeit not statistically significant) rate than control RMs following repeated intrarectal challenges with a pathogenic SIV clone. All animals in the present experiment expressed the elite control-associated major histocompatibility complex class I (MHC-I) molecule Mamu-B*08 that binds immunodominant epitopes in Vif and Nef. Though preliminary, these results provide tantalizing evidence that the protective efficacy of vaccine-elicited CD8+T cells may be greater than previously thought. Future studies should examine if vaccine-induced cellular immunity can prevent systemic viral replication in RMs that do not express MHC-I alleles associated with elite control of SIV infection.

scholarly journals P03.22 Repolarization of tumor-associated macrophages for immunotherapy of tumors with diverse major histocompatibility complex class I expression

2020 ◽  
Vol 8 (Suppl 2) ◽  
pp. A31.1-A31
Author(s):  
A Piataková ◽  
I Poláková ◽  
M Šmahel
Keyword(s):  
Major Histocompatibility Complex ◽  
Cytotoxic Effect ◽  
Complex Class ◽  
Mhc I ◽  
Mhc Ii ◽  
Histocompatibility Complex ◽  
Tnf Α ◽  
Tumor Types ◽  
Combined Immunotherapy

BackgroundDepletion of tumor-associated macrophages (TAMs), which are regarded as M2, pro-tumor cells, is one of the strategies for cancer treatment. However, repolarization of TAMs to the M1 anti-tumor phenotype could constitute an immunotherapeutic alternative for tumors with defective major histocompatibility complex class I (MHC-I), where the anti-tumor effect of cytotoxic CD8+ T cells could be limited.Materials and MethodsIn this study, we characterized TAMs from mouse tumor models of human papillomavirus 16-associated tumors, characterized by either reversibly (TC-1/A9) or irreversibly (TC-1/dB2m) downregulated MHC-I expression. Tumors were treated with DNA immunization against the papillomaviral E7 oncoprotein combined with intraperitoneal injection of the synthetic oligodeoxynucleotide ODN1826, a Toll-like receptor 9 agonist. TAMs were characterized ex vivo by flow cytometry. In vitro, F4/80+ TAMs from naïve tumors were stimulated to M1 or M2 phenotype and co-cultures with TC-1/A9 or TC-1/dB2m cells were established. The cytotoxic effect of polarized TAMs was investigated, and the role of nitric oxide (NO) and tumor necrosis factor (TNF)-α was examined. Finally, interleukin (IL)-10, IL-12 and TNF-α concentrations were determined by ELISA in the culture media from polarized TAMs.ResultsWe demonstrated that TAMs infiltrated both tumor types and this effect was moderately enhanced after combined immunotherapy. Increase in MHC-II molecules, broadly regarded as an M1 marker, was observed solely in TAMs from treated TC-1/A9 tumors. In contrast, TAMs from TC-1/dB2m tumors expressed high MHC-II levels, regardless of the treatment. Therefore, the new CD38+/Egr2+ classification1 was applied and showed to be a better descriptive parameter for M1/M2 TAMs, respectively, because the number of Egr2+ TAMs decreased in both tumor types after combined immunotherapy. While CD38+ TAMs were significantly increased after treatment of TC-1/A9 tumors, they did not increase substantially in TC-1/dB2m tumors. In vitro, co-cultures with tumor cells resulted in increase of NO production by M1 TAMs. However, NO and TNF-α contributed to the cytotoxic effect only in TAMs from TC-1/A9 tumor. Finally, in vitro polarized M1 TAMs were able to produce TNF-α and IL-10 but not IL-12.ConclusionsOur results showed different effects of immunostimulation on cytotoxicity of TAMs from tumors with distinct MHC-I expression. While TAMs from TC-1/A9 tumors acquired M1 phenotype and became cytotoxic, TAMs from TC-1/dB2m tumors were more resistant to repolarization. This project was supported by grants GA19–00816S provided by the Czech Science Foundation and LQ1604 provided by the Ministry of Education, Youth and Sports of the Czech Republic.ReferenceJablonski KA, Amici SA, Webb LM, Ruiz-Rosado JdD, Popovich PG, Partida-Sanchez S, Arellano M. Novel Markers to Delineate Murine M1 and M2 Macrophages. PLoS ONE 2015; 10(12); 1–25.Disclosure InformationA. Piataková: None. I. Poláková: None. M. Šmahel: None.

scholarly journals Persistent Infection of Rhesus Macaques by the Rev-Independent Nef(−) Simian Immunodeficiency Virus SIVmac239: Replication Kinetics and Genomic Stability

1999 ◽  
Vol 73 (7) ◽  
pp. 6159-6165 ◽  
Author(s):  
Agneta S. von Gegerfelt ◽  
Vladimir Liska ◽  
Nancy B. Ray ◽  
Harold M. McClure ◽  
Ruth M. Ruprecht ◽  
...  
Keyword(s):  
Simian Immunodeficiency Virus ◽  
Rhesus Macaques ◽  
Present Report ◽  
Viral Loads ◽  
Humoral Immune ◽  
Constitutive Transport Element ◽  
Immunodeficiency Virus ◽  
Responsive Element

ABSTRACT We generated previously a Nef(−), replication-competent clone of SIVmac239 in which the Rev protein and the Rev-responsive element were replaced by the constitutive transport element (CTE) of simian retrovirus type 1 (A. S. von Gegerfelt and B. K. Felber, Virology 232:291–299, 1997). In the present report, we show that this virus was able to infect and replicate in rhesus macaques. The Rev-independent Nef(−) simian immunodeficiency virus induced a persistent humoral immune response in all monkeys, although viral loads were very low. Upon propagation in the monkeys, the genotype remained stable and the virus retained its in vitro growth characteristics. The infected monkeys showed normal hematological values and no signs of disease at more than 18 months post-virus exposure. Therefore, replacement of the essential Rev regulation by the CTE generated a virus variant that retained its replicative capacity both in vitro and in vivo, albeit at low levels.

scholarly journals A Truncated Form of Nef Selected during Pathogenic Reversion of Simian Immunodeficiency Virus SIVmac239Δnef Increases Viral Replication

2003 ◽  
Vol 77 (2) ◽  
pp. 1245-1256 ◽  
Author(s):  
Lisa A. Chakrabarti ◽  
Karin J. Metzner ◽  
Tijana Ivanovic ◽  
Hua Cheng ◽  
Jean Louis-Virelizier ◽  
...  
Keyword(s):  
T Cell ◽  
Viral Replication ◽  
Simian Immunodeficiency Virus ◽  
Rhesus Macaques ◽  
Premature Stop Codon ◽  
Cell Depletion ◽  
Partial Recovery ◽  
Wild Type ◽  
T Cell Depletion ◽  
Immunodeficiency Virus

ABSTRACT The live, attenuated vaccine simian immunodeficiency virus SIVmac239Δnef efficiently protects rhesus macaques against infection with wild-type SIVmac but occasionally causes CD4+ T-cell depletion and progression to simian AIDS (SAIDS). Virus recovered from a vaccinated macaque (Rh1490) that progressed to SAIDS had acquired an additional deletion in the nef gene, resulting in a frameshift that restored the original nef open reading frame (R. I. Connor, D. C. Montefiori, J. M. Binley, J. P. Moore, S. Bonhoeffer, A. Gettie, E. A. Fenamore, K. E. Sheridan, D. D. Ho, P. J. Dailey, and P. A. Marx, J. Virol. 72:7501-7509, 1998). Intravenous inoculation of the Rh1490 viral isolate into four naive rhesus macaques induced CD4+ T-cell depletion and disease in three out of four animals within 2 years, indicating a restoration of virulence. A DNA fragment encompassing the truncated nef gene amplified from the Rh1490 isolate was inserted into the genetic backbone of SIVmac239. The resulting clone, SIVmac239-Δ2nef, expressed a Nef protein of approximately 23 kDa, while the original SIVmac239Δnef clone expressed a shorter protein of 8 kDa. The revertant form of Nef did not cause downregulation of CD4, CD3, or major histocompatibility complex class I. The infectivity of SIVmac239-Δ2nef was similar to that of SIVmac239Δnef in single-cycle assays using indicator cell lines. In contrast, SIVmac239-Δ2nef replicated more efficiently than SIVmac239Δnef in peripheral blood mononuclear cell (PBMC) cultures infected under unstimulated conditions. The p27 Gag antigen levels in SIVmac239-Δ2nef-infected cultures were still lower than those obtained with wild-type SIVmac239, consistent with a partial recovery of Nef function. The transcriptional activity of long terminal repeat (LTR)-luciferase constructs containing the nef deletions did not differ markedly from that of wild-type LTR. Introduction of a premature stop codon within Nef-Δ2 abolished the replicative advantage in PBMCs, demonstrating that the Nef-Δ2 protein, rather than the structure of the U3 region of the LTR, was responsible for the increase in viral replication. Taken together, these results show that SIV with a deletion in the nef gene can revert to virulence and that expression of a form of nef with multiple deletions may contribute to this process by increasing viral replication.

scholarly journals High Levels of a Major Histocompatibility Complex II–Self Peptide Complex on Dendritic Cells from the T Cell Areas of Lymph Nodes

1997 ◽  
Vol 186 (5) ◽  
pp. 665-672 ◽  
Author(s):  
Kayo Inaba ◽  
Maggie Pack ◽  
Muneo Inaba ◽  
Hiraki Sakuta ◽  
Frank Isdell ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
T Cell ◽  
Lymph Nodes ◽  
Mhc I ◽  
Peptide Complex ◽  
Mhc Ii ◽  
Histocompatibility Complex ◽  
Peripheral Lymph ◽  
Free Media ◽  
Very High

T lymphocytes recirculate continually through the T cell areas of peripheral lymph nodes. During each passage, the T cells survey the surface of large dendritic cells (DCs), also known as interdigitating cells. However, these DCs have been difficult to release from the lymph node. By emphasizing the use of calcium-free media, as shown by Vremec et al. (Vremec, D., M. Zorbas, R. Scollay, D.J. Saunders, C.F. Ardavin, L. Wu, and K. Shortman. 1992. J. Exp. Med. 176:47–58.), we have been able to release and enrich DCs from the T cell areas. The DCs express the CD11c leukocyte integrin, the DEC-205 multilectin receptor for antigen presentation, the intracellular granule antigens which are recognized by monoclonal antibodies M342, 2A1, and MIDC-8, very high levels of MHC I and MHC II, and abundant accessory molecules such as CD40, CD54, and CD86. When examined with the Y-Ae monoclonal which recognizes complexes formed between I-Ab and a peptide derived from I-Eα, the T cell area DCs expressed the highest levels. The enriched DCs also stimulated a T-T hybridoma specific for this MHC II–peptide complex, and the hybridoma underwent apoptosis. Therefore DCs within the T cell areas can be isolated. Because they present very high levels of self peptides, these DCs should be considered in the regulation of self reactivity in the periphery.

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