Resistance to collagen-induced arthritis in a nonhuman primate species maps to the major histocompatibility complex class I region

MHC-DRB alleles with amino acids Val11, Phe13, and the shared epitopes promote collagen-induced arthritis and a rapid IgG1 response in Filipino cynomolgus macaques

Macaques are useful animal models for studying the pathogenesis of rheumatoid arthritis (RA) and the development of anti-rheumatic drugs. The purpose of this study was to identify the major histocompatibility complex (MHC) polymorphisms associated with the pathology of collagen-induced arthritis (CIA) and anti-collagen IgG induction in a cynomolgus macaque model, as MHC polymorphisms affect the onset of CIA in other animal models. Nine female Filipino cynomolgus macaques were immunized with bovine type II collagen (b-CII) to induce CIA, which was diagnosed clinically by scoring the symptoms of joint swelling over 9 weeks. MHC polymorphisms and anti-b-CII antibody titers were compared between symptomatic and asymptomatic macaques. Four of 9 (44%) macaques were defined as the CIA-affected group. Anti-b-CII IgG in the affected group increased in titer approximately 3 weeks earlier compared with the asymptomatic group. The mean plasma IgG1 titer in the CIA-affected group was significantly higher (p < 0.05) than that of the asymptomatic group. Furthermore, the cynomolgus macaque MHC (Mafa)-DRB1*10:05 or Mafa-DRB1*10:07 alleles, which contain the well-documented RA-susceptibility five amino acid sequence known as the shared epitope (SE) in positions 70 to 74, with valine at position 11 (Val11, V11) and phenylalanine at position 13 (Phe13, F13), were detected in the affected group. In contrast, no MHC polymorphisms specific to the asymptomatic group were identified. In conclusion, the presence of V11 and F13 along with SE in the MHC-DRB1 alleles seems essential for the production of IgG1 and the rapid induction of severe CIA in female Filipino cynomolgus macaques.

Long-read assembly of major histocompatibility complex and killer cell immunoglobulin-like receptor genome regions in cynomolgus macaque

BACKGROUND

The major histocompatibility complex (MHC) and the killer cell immunoglobulin-like receptors (KIR) are key regulators of immune responses. The cynomolgus macaque, an Old World monkey species, can be applied as an important preclinical model for studying human diseases, including coronavirus disease 2019 (COVID-19). Several MHC-KIR combinations have been associated with either a poor or good prognosis. Therefore, macaques with a well-characterized immunogenetic profile may improve drug evaluation and speed up vaccine development. At present, a complete overview of the MHC and KIR haplotype organizations in cynomolgus macaques is lacking, and characterization by conventional techniques is hampered by the extensive expansion of the macaque MHC-B region that complicates the discrimination between genes and alleles.

METHODS

We assembled complete MHC and KIR genomic regions of cynomolgus macaque using third-generation long-read sequencing approach. We identified functional Mafa-B loci at the transcriptome level using locus-specific amplification in a cohort of 33 Vietnamese cynomolgus macaques.

RESULTS

This is the first physical mapping of complete MHC and KIR gene regions in a Vietnamese cynomolgus macaque. Furthermore, we identified four functional Mafa-B loci (B2, B3, B5, and B6) and showed that alleles of the Mafa-I*01, -B*056, -B*034, and -B*001 functional lineages, respectively, are highly frequent in the Vietnamese cynomolgus macaque population.

CONCLUSION

The insights into the MHC and KIR haplotype organizations and the level of diversity may refine the selection of animals with specific genetic markers for future medical research.

Predictors of Subcutaneous Injection Site Reactions to Sustained-Release Buprenorphine in Rhesus Macaques (Macaca mulatta)

Subcutaneous injection site reactions to sustained-release buprenorphine hydrochloride (Buprenorphine SR) in macaques have been reported in only a single case report. In the current study, we evaluated the incidence rate and predictors of buprenorphine SR reactions in the subcutaneous tissue of rhesus macaques (Macaca mulatta) based on retrospective review of macaque buprenorphine SR injection records. Potentially predictive variables were identified with logistic regression modeling and were evaluated using model selection based on Akaike information criterion. Record review revealed sub- cutaneous tissue reactions occurred in 52 (3%) of 1559 injections and were noted between 4 and 311 d after injection. Model selection showed that body weight and MHC allele Mamu-B*29 were the best predictors of subcutaneous reactions. Based on these results, we recommend consideration of potential risk factors prior to the administration of buprenorphine SR to a rhesus macaque. In addition, the authors advise that using the highest concentration of buprenorphine SR available may reduce injection site reaction rates due to the injection of less copolymer.

The establishment of a rheumatoid arthritis primate model in Macaca fascicularis

Background

Rheumatoid arthritis (RA) is a long-term autoimmune disorder that mostly affects the joints and leads to the destruction of cartilage. An RA model in non-human primates is especially useful because of their close phylogenetic relationship to humans in terms of cross-reactivity to compounds developed using modern drug technologies.

Methods

We used a collagen-induced arthritis (CIA) model in Macaca fascicularis. CIA was induced by the immunization of chicken type II collagen. Swelling was measured as the longitudinal and transverse axes of 16 proximal interphalangeal joints.

Results

A new system for visual evaluation was created, with a perfect score of 16. Individual behavioral analysis was also conducted. Serum was collected once a week after the first immunization. Blood chemistry and inflammatory cytokine parameters were higher in the CIA group than in the wild type group.

Conclusion

In conclusion, we established CIA in M. fascicularis, and the results can be used for drug evaluation models.

MHC class I allele diversity in cynomolgus macaques of Vietnamese origin

Cynomolgus macaques (Macaca fascicularis, Mafa) have been used as important experimental animal models for carrying out biomedical researches. The results of biomedical experiments strongly depend on the immunogenetic background of animals, especially on the diversity of major histocompatibility complex (MHC) alleles. However, there is much less information available on the polymorphism of MHC class I genes in cynomolgus macaques, than is currently available for humans. In this study, we have identified 40 Mafa-A and 60 Mafa-B exons 2 and 3 sequences from 30 unrelated cynomolgus macaques of Vietnamese origin. Among these alleles, 28 are novel. As for the remaining 72 known alleles, 15 alleles are shared with other cynomolgus macaque populations and 32 are identical to alleles previously reported in other macaque species. A potential recombination event was observed between Mafa-A1*091:02 and Mafa-A1*057:01. In addition, the Mafa-A1 genes were found to be more diverse than human HLA-A and the functional residues for peptide binding sites (PBS) or TCR binding sites (TBS) in Mafa-A1 have greater variability than that for non-PBS or non-TBS regions. Overall, this study provides important information on the diversity of Mafa-A and Mafa-B alleles from Vietnamese origin, which may help researchers to choose the most appropriate animals for their studies.

Anti-carbamylated protein antibodies precede disease onset in monkeys with collagen-induced arthritis

Background

Rheumatoid factor (RF), anti-citrullinated protein antibodies (ACPA) and anti-carbamylated protein (anti-CarP) antibodies are rheumatoid arthritis (RA)-associated autoantibodies. Besides their presence in human serum, anti-CarP antibodies have also been described in rodent models of arthritis, while ACPA are not consistently detectable. Data on these RA-associated autoantibodies in primates are not available. Therefore, we investigated the presence of RF, anti-CarP antibodies and ACPA in rhesus monkeys before and after collagen-induced arthritis immunizations.

Methods

In previous studies, arthritis was induced in groups of rhesus monkeys by immunisation with collagen following pre-treatment with placebo, abatacept or Roactemra. Previously collected serum was used to measure, autoantibodies by ELISA, detecting anti-CarP antibodies, RF-IgM and antibodies against CCP2, citrullinated myelin basic protein and citrullinated fibrinogen.

Results

Out of the three autoantibodies, only anti-CarP antibodies were detectable in resus monkeys with arthritis. RF-IgM and ACPA were undetectable and below the detection limit of the ELISA. The level of anti-CarP antibodies increases over time and, similar to in humans and mice, these autoantibodies were already detectable before clinical disease onset. Furthermore, preventive treatment with abatacept (CTLA4/IgG1-Fc fusion protein) inhibited the development of anti-CarP antibodies after immunization, while this was less evident for preventive Roactemra (anti-IL6-receptor) treatment. Moreover, disease progression was only reduced following abatacept treatment.

Conclusion

Rhesus monkeys develop anti-CarP antibodies upon induction of collagen-induced arthritis, while we were unable to detect RF or ACPA. Also, the development of anti-CarP antibodies could be inhibited by preventive abatacept treatment.

Primate autoimmune disease models; lost for translation?

Replacement, reduction and refinement (the 3R's) are the leading principles in translational research with animals. To be useful a model should also be clinically Relevant (the 4th R). Work in a non-human primate model of multiple sclerosis, the experimental autoimmune encephalomyelitis model, reveals an inherent conflict among these 4R principles. The impossibility to harmonize all 4R's forms a major challenge when the model is applied in preclinical drug development.

Co-evolution of the MHC class I and KIR gene families in rhesus macaques: ancestry and plasticity

Researchers dealing with the human leukocyte antigen (HLA) class I and killer immunoglobulin receptor (KIR) multi‐gene families in humans are often wary of the complex and seemingly different situation that is encountered regarding these gene families in Old World monkeys. For the sake of comparison, the well‐defined and thoroughly studied situation in humans has been taken as a reference. In macaques, both the major histocompatibility complex class I and KIR gene families are plastic entities that have experienced various rounds of expansion, contraction, and subsequent recombination processes. As a consequence, haplotypes in macaques display substantial diversity with regard to gene copy number variation. Additionally, for both multi‐gene families, differential levels of polymorphism (allelic variation), and expression are observed as well. A comparative genetic approach has allowed us to answer questions related to ancestry, to shed light on unique adaptations of the species’ immune system, and to provide insights into the genetic events and selective pressures that have shaped the range of these gene families.

The establishment of a porcine rheumatoid arthritis model: Collagen induced arthritis minipig model

Rheumatoid arthritis (RA) research has been largely dependent on collagen induced arthritis (CIA) rodent models, however, they may not translate well to humans due to innate differences in the size, physiology and lifespan. The present study aimed to establish a CIA porcine model with the physical, hematological, histopathological and etiological properties closer to their human equivalent in an attempt to better meet the needs of RA research. Three month old minipigs were administered of bovine type II collagen (CII) emulsified with complete Freund's adjuvants on Day 1 and incomplete Freund's adjuvants on Day 22, via an intradermal or intra-articular route. The clinical, radiological and hematological assessments of immunized animals were made periodically until Day 43, during which period the onset and progression of arthritis was recorded and characterized. In addition, the histopathological and micro-tomographic assessments of the cartilage degradation with regard to mononuclear cell infiltration, and joint deformity indicated a higher severity in the intradermal injection group over the intra-articular group. With confirmation of the susceptibility to heterogeneous CII for arthritis induction in minipig, the potential suitability of this test system as a large animal model for RA has been demonstrated.

Safety, Biodistribution, and Efficacy of an AAV-5 Vector Encoding Human Interferon-Beta (ART-I02) Delivered via Intra-Articular Injection in Rhesus Monkeys with Collagen-Induced Arthritis

Preclinical studies to assess biodistribution, safety, and initial efficacy of ART-I02, an adeno-associated type 5 (rAAV5) vector expressing human interferon β (hIFN-β), were performed in a total of 24 rhesus monkeys with collagen-induced arthritis. All monkeys were naïve or showed limited neutralizing antibody (Nab) titers to AAV5 at the start of the study. Animals were injected with a single intra-articular dose of ART-I02 or placebo, consisting of 3.2×10(13) vg (Dose A=maximum feasible dose), 4.58×10(12) vg (Dose B), or placebo in the first affected finger joint, the ipsilateral knee, and ankle joint at the same time point. Animals were monitored for clinical parameters and well-being with a maximum of 4 weeks, with the option that the severity of arthritis could necessitate an earlier time point of sacrifice. No adverse events were noted after injection of ART-I02. No abnormalities were observed after histological evaluation of all organs. At both dose levels, immunohistochemical staining indicated expression of hIFN-β. In animals injected with Dose A, we observed stabilization or a reduction in swelling in the finger joint in which vector was administered. The highest copy numbers of vector DNA were detected in synovial tissue of the injected joint and the draining lymph node of the injected knee. High titers of Nab to rAAV5 were observed at the end of the study. Five monkeys developed an rAAV5-specific T-cell response. Two monkeys developed Nab to hIFN-β. In conclusion, intra-articular injection of ART-I02 was well-tolerated and did not induce adverse events. After administration of Dose A of ART-I02, we observed a beneficial effect on joint swelling, substantiated by decreased histological inflammation and bone erosion scores. A GMP vector for clinical application has been manufactured and is currently being tested in GLP rodent studies, with the aim to move forward to a clinical trial.

Clinical efficacy of a new CD28-targeting antagonist of T cell co-stimulation in a non-human primate model of collagen-induced arthritis

T cells have a central pathogenic role in the aetiopathogenesis of rheumatoid arthritis (RA), and are therefore a favoured target of immunotherapy aiming at physical or functional elimination. Here we report an efficacy test of FR104, a new co-stimulation inhibitor directly targeting CD28 on T cells, in a translationally relevant model, the rhesus monkey model of collagen-induced arthritis (CIA). As a relevant comparator we used abatacept [cytotoxic T lymphocyte antigen immunoglobulin (CTLA Ig)], an antagonist of CTLA-4 binding to CD80/86 clinically approved for treatment of RA. Treatment with either compound was started at the day of CIA induction. Although FR104 previously demonstrated a higher control of T cell responses in vitro than abatacept, both compounds were equally potent in the suppression of CIA symptoms and biomarkers, such as the production of C-reactive protein (CRP) and interleukin (IL)-6 and anti-collagen type II (CII) serum antibody (IgM/IgG). However, in contrast to abatacept, FR104 showed effective suppression of CII-induced peripheral blood mononuclear cell (PBMC) proliferation. The current study demonstrates a strong potential of the new selective CD28 antagonist FR104 for treatment of RA.

The preclinical pharmacology of the high affinity anti-IL-6R Nanobody® ALX-0061 supports its clinical development in rheumatoid arthritis

Introduction

The pleiotropic cytokine interleukin-6 (IL-6) plays an important role in the pathogenesis of different diseases, including rheumatoid arthritis (RA). ALX-0061 is a bispecific Nanobody® with a high affinity and potency for IL-6 receptor (IL-6R), combined with an extended half-life by targeting human serum albumin. We describe here the relevant aspects of its in vitro and in vivo pharmacology.

Methods

ALX-0061 is composed of an affinity-matured IL-6R-targeting domain fused to an albumin-binding domain representing a minimized two-domain structure. A panel of different in vitro assays was used to characterize the biological activities of ALX-0061. The pharmacological properties of ALX-0061 were examined in cynomolgus monkeys, using plasma levels of total soluble (s)IL-6R as pharmacodynamic marker. Therapeutic effect was evaluated in a human IL-6-induced acute phase response model in the same species, and in a collagen-induced arthritis (CIA) model in rhesus monkeys, using tocilizumab as positive control.

Results

ALX-0061 was designed to confer the desired pharmacological properties. A 200-fold increase of target affinity was obtained through affinity maturation of the parental domain. The high affinity for sIL-6R (0.19 pM) translated to a concentration-dependent and complete neutralization of sIL-6R in vitro. In cynomolgus monkeys, ALX-0061 showed a dose-dependent and complete inhibition of hIL-6-induced inflammatory parameters, including plasma levels of C-reactive protein (CRP), fibrinogen and platelets. An apparent plasma half-life of 6.6 days was observed after a single intravenous administration of 10 mg/kg ALX-0061 in cynomolgus monkeys, similar to the estimated expected half-life of serum albumin. ALX-0061 and tocilizumab demonstrated a marked decrease in serum CRP levels in a non-human primate CIA model. Clinical effect was confirmed in animals with active drug exposure throughout the study duration.

Conclusions

ALX-0061 represents a minimized bispecific biotherapeutic of 26 kDa, nearly six times smaller than monoclonal antibodies. High in vitro affinity and potency was demonstrated. Albumin binding as a half-life extension technology resulted in describable and expected pharmacokinetics. Strong IL-6R engagement was shown to translate to in vivo effect in non-human primates, demonstrated via biomarker deregulation as well as clinical effect. Presented results on preclinical pharmacological properties of ALX-0061 are supportive of clinical development in RA.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0651-0) contains supplementary material, which is available to authorized users.

The translational value of non-human primates in preclinical research on infection and immunopathology

The immune system plays a central role in the defense against environmental threats - such as infection with viruses, parasites or bacteria - but can also be a cause of disease, such as in the case of allergic or autoimmune disorders. In the past decades the impressive development of biotechnology has provided scientists with biological tools for the development of highly selective treatments for the different types of disorders. However, despite some clear successes the translation of scientific discoveries into effective treatments has remained challenging. The often-disappointing predictive validity of the preclinical animal models that are used in the selection of the most promising vaccine or drug candidates is the Achilles heel in the therapy development process. This publication summarizes the relevance and usage of non-human primates as pre-clinical model in infectious and autoimmune diseases, in particular for biologicals, which due to their high species-specificity are inactive in lower species.

PDL241, a novel humanized monoclonal antibody, reveals CD319 as a therapeutic target for rheumatoid arthritis

Introduction

Targeting the CD20 antigen has been a successful therapeutic intervention in the treatment of rheumatoid arthritis (RA). However, in some patients with an inadequate response to anti-CD20 therapy, a persistence of CD20^- plasmablasts is noted. The strong expression of CD319 on CD20^- plasmablast and plasma cell populations in RA synovium led to the investigation of the potential of CD319 as a therapeutic target.

Methods

PDL241, a novel humanized IgG₁ monoclonal antibody (mAb) to CD319, was generated and examined for its ability to inhibit immunoglobulin production from plasmablasts and plasma cells generated from peripheral blood mononuclear cells (PBMC) in the presence and absence of RA synovial fibroblasts (RA-SF). The in vivo activity of PDL241 was determined in a human PBMC transfer into NOD scid IL-2 gamma chain knockout (NSG) mouse model. Finally, the ability of PDL241 to ameliorate experimental arthritis was evaluated in a collagen-induced arthritis (CIA) model in rhesus monkeys.

Results

PDL241 bound to plasmablasts and plasma cells but not naïve B cells. Consistent with the binding profile, PDL241 inhibited the production of IgM from in vitro PBMC cultures by the depletion of CD319⁺ plasmablasts and plasma cells but not B cells. The activity of PDL241 was dependent on an intact Fc portion of the IgG₁ and mediated predominantly by natural killer cells. Inhibition of IgM production was also observed in the human PBMC transfer to NSG mouse model. Treatment of rhesus monkeys in a CIA model with PDL241 led to a significant inhibition of anti-collagen IgG and IgM antibodies. A beneficial effect on joint related parameters, including bone remodeling, histopathology, and joint swelling was also observed.

Conclusions

The activity of PDL241 in both in vitro and in vivo models highlights the potential of CD319 as a therapeutic target in RA.

The value of extended pedigrees for next-generation analysis of complex disease in the rhesus macaque

Complex diseases (e.g., cardiovascular disease and type 2 diabetes, among many others) pose the biggest threat to human health worldwide and are among the most challenging to investigate. Susceptibility to complex disease may be caused by multiple genetic variants (GVs) and their interaction, by environmental factors, and by interaction between GVs and environment, and large study cohorts with substantial analytical power are typically required to elucidate these individual contributions. Here, we discuss the advantages of both power and feasibility afforded by the use of extended pedigrees of rhesus macaques (Macaca mulatta) for genetic studies of complex human disease based on next-generation sequence data. We present these advantages in the context of previous research conducted in rhesus macaques for several representative complex diseases. We also describe a single, multigeneration pedigree of Indian-origin rhesus macaques and a sample biobank we have developed for genetic analysis of complex disease, including power of this pedigree to detect causal GVs using either genetic linkage or association methods in a variance decomposition approach. Finally, we summarize findings of significant heritability for a number of quantitative traits that demonstrate that genetic contributions to risk factors for complex disease can be detected and measured in this pedigree. We conclude that the development and application of an extended pedigree to analysis of complex disease traits in the rhesus macaque have shown promising early success and that genome-wide genetic and higher order -omics studies in this pedigree are likely to yield useful insights into the architecture of complex human disease.

Induction of experimental autoimmune encephalomyelitis with recombinant human myelin oligodendrocyte glycoprotein in incomplete Freund's adjuvant in three non-human primate species

The experimental autoimmune encephalitis (EAE) model is used for preclinical research into the pathogenesis of multiple sclerosis (MS), mostly in inbred, specific pathogen free (SPF)-raised laboratory mice. However, the naive state of the laboratory mouse immune system is considered a major hurdle in the translation of principles from the EAE model to the MS patient. Non-human primates (NHP) have an immune system harboring T- and B-cell memory against environmental antigens, similar as in humans. We sought to further refine existing NHP EAE models, which may help to bridge the gab between mouse EAE models and MS. We report here on new EAE models in three NHP species: rhesus monkeys (Macaca mulatta), cynomolgus monkeys (Macaca fascicularis) and common marmosets (Callithrix jacchus). EAE was induced with recombinant human myelin oligodendrocyte glycoprotein extracellular domain (1–125) (rhMOG) formulated in incomplete Freund’s adjuvant (IFA). IFA lacks the bacterial antigens that are present in complete Freund’s adjuvant (CFA), which are notorious for the induction of discomforting side effects. Clinically evident EAE could be induced in two out of five rhesus monkeys, six out of six cynomolgus monkeys and six out of six common marmosets. In each of these species, the presence of an early, high anti-rhMOG IgM response is correlated with EAE with an earlier onset and more severe disease course. Animals without an early high IgM response either did not develop disease (rhesus monkeys) or developed only mild signs of neurological deficit (marmoset and cynomolgus monkeys).

The significance of non-human primates as preclinical models of human arthritic disease

BACKGROUND

The broad immunological gap between inbred SPF-raised strains of mice and rats and the diverse rheumatoid arthritis (RA) patient population limits the predictive value of the existing disease models for clinical success of new therapies, in particular for those using highly specific biologicals.

OBJECTIVE

This review argues that because of their closer immunological and physiological proximity to patients, disease models in non-human primates (NHPs) may bridge this gap and help reduce the failure of many (± 80%) new therapies in clinical trials. In various research areas, NHPs are an accepted intermediate between disease models in rodents and the ultimate introduction for clinical use in patients. However, with the exception of transplantation, this is not the case for immune-mediated inflammatory disorders, such as RA, although useful preclinical models are being developed.

METHOD

The validity and use of the rhesus monkey model of collagen-induced arthritis as a preclinical RA model is reviewed. The discussion comprises present genetic and immunological aspects, biomarkers, and an overview of published preclinical therapy evaluations.

CONCLUSION

It is time to consider the use of NHPs with a greater evolutionary proximity to humans as models for preclinical evaluation of new human-specific drugs for arthritic disease.

New drug discovery strategies for rheumatoid arthritis: a niche for nonhuman primate models to address systemic complications in inflammatory arthritis

INTRODUCTION

Despite the tremendous advances made in the treatment of rheumatoid arthritis (RA), there is still excess mortality observed in RA patients, which is mainly caused by cardiovascular disease (CVD). Altered lipid metabolism plays a major role in the etiology of CVD. A second common complication observed in RA patients is anemia. Both conditions are serious, reduce quality of life and are undertreated.

AREAS COVERED

The authors postulate that there is a specific niche for nonhuman primate models of inflammatory arthritis to address these systemic complications that occur in RA. Furthermore, the authors postulate that these nonhuman primate models are a useful platform to unveil the mechanisms underlying dyslipidemia and anemia, which are responsible for the manifestation of these complications.

EXPERT OPINION

The presence of currently untreated systemic complications of RA, such as dyslipidemia and anemia, provides interesting opportunities to include these in the preclinical evaluation of new therapies. In the selection of relevant models for the evaluation of new treatments for RA or the identification of new targets for therapy, we postulate that nonhuman primates should be considered as a valid preclinical model. Because of their closer immunological and physiological proximity to humans, these models in nonhuman primates can be valuable for studying disease-related aspects that cannot be addressed in rodent models.

Collagen-induced arthritis in common marmosets: a new nonhuman primate model for chronic arthritis

INTRODUCTION

There is an ever-increasing need for animal models to evaluate efficacy and safety of new therapeutics in the field of rheumatoid arthritis (RA). Particularly for the early preclinical evaluation of human-specific biologicals targeting the progressive phase of the disease, there is a need for relevant animal models. In response to this requirement we set out to develop a model of collagen-induced arthritis (CIA) in a small-sized nonhuman primate species (300 to 400 g at adult age); that is, the common marmoset (Callithrix jacchus).

METHODS

Twenty-two animals divided into three experiments were immunized with collagen type II (CII) of either bovine or chicken origin with different immunization strategies. The animals were analyzed for clinical manifestation of arthritis, hematology and clinical chemistry, immunological responses against CII and histopathological features of the arthritis.

RESULTS

Clinically manifest arthritis was observed in almost 100% (21 out of 22) of the animals. Fifty percent of the animals developed semi-acute CIA while the other 50% displayed a more chronic disease. Both cellular (CD3/CD4 and CD3/CD8) and humoral responses (IgM and IgG) against CII were involved in the development of the disease. Besides mild histopathological changes in bone and cartilage, severe inflammation in extraarticular tissues like periosteum and subcutaneous tissues was observed.

CONCLUSIONS

This new model in marmosets more closely resembles chronic RA with respect to the chronic disease course and pathomorphological presentation than the more acute monophasic and destructive CIA model in macaques. This model can therefore fill a niche in preclinical testing of new human specific therapeutics.

Brain antigens in functionally distinct antigen-presenting cell populations in cervical lymph nodes in MS and EAE

Drainage of central nervous system (CNS) antigens to the brain-draining cervical lymph nodes (CLN) is likely crucial in the initiation and control of autoimmune responses during multiple sclerosis (MS). We demonstrate neuronal antigens within CLN of MS patients. In monkeys and mice with experimental autoimmune encephalomyelitis (EAE) and in mouse models with non-inflammatory CNS damage, the type and extent of CNS damage was associated with the frequencies of CNS antigens within the cervical lymph nodes. In addition, CNS antigens drained to the spinal-cord-draining lumbar lymph nodes. In human MS CLN, neuronal antigens were present in pro-inflammatory antigen-presenting cells (APC), whereas the majority of myelin-containing cells were anti-inflammatory. This may reflect a different origin of the cells or different drainage mechanisms. Indeed, neuronal antigen-containing cells in human CLN did not express the lymph node homing receptor CCR7, whereas myelin antigen-containing cells in situ and in vitro did. Nevertheless, CLN from EAE-affected CCR7-deficient mice contained equal amounts of myelin and neuronal antigens as wild-type mice. We conclude that the type and frequencies of CNS antigens within the CLN are determined by the type and extent of CNS damage. Furthermore, the presence of myelin and neuronal antigens in functionally distinct APC populations within MS CLN suggests that differential immune responses can be evoked.

A snapshot of the Mamu-B genes and their allelic repertoire in rhesus macaques of Chinese origin

The major histocompatibility complex class I gene repertoire was investigated in a large panel of rhesus macaques of Chinese origin. As observed in Indian animals, subjects of Chinese derivation display Mamu-B gene copy number variation, and the sum of expressed genes varies among haplotypes. In addition, these genes display differential transcription levels. The majority of the Mamu-B alleles discovered during this investigation appear to be unique for the population studied. Only one particular Mamu-B haplotype is shared between Indian and Chinese animals, and it must have been present in the progenitor stock. Hence, the data highlight the fact that most allelic polymorphism, and most of the Mamu-B haplotypes themselves, are of relatively recent origin and were most likely generated after the separation of the Indian and Chinese rhesus macaque populations.

Comprehensive characterization of MHC class II haplotypes in Mauritian cynomolgus macaques

There are currently no nonhuman primate models with fully defined major histocompatibility complex (MHC) class II genetics. We recently showed that six common MHC haplotypes account for essentially all MHC diversity in cynomolgus macaques (Macaca fascicularis) from the island of Mauritius. In this study, we employ complementary DNA cloning and sequencing to comprehensively characterize full length MHC class II alleles expressed at the Mafa-DPA, -DPB, -DQA, -DQB, -DRA, and -DRB loci on the six common haplotypes. We describe 34 full-length MHC class II alleles, 12 of which are completely novel. Polymorphism was evident at all six loci including DPA, a locus thought to be monomorphic in rhesus macaques. Similar to other Old World monkeys, Mauritian cynomolgus macaques (MCM) share MHC class II allelic lineages with humans at the DQ and DR loci, but not at the DP loci. Additionally, we identified extensive sharing of MHC class II alleles between MCM and other nonhuman primates. The characterization of these full-length-expressed MHC class II alleles will enable researchers to generate MHC class II transferent cell lines, tetramers, and other molecular reagents that can be used to explore CD4+ T lymphocyte responses in MCM.

Preclinical models of arthritic disease in non-human primates

The costs for the development of new drugs have increased dramatically over the past 30 years. One of the main reasons for this increase is the low success rate of new drugs being approved for patient use, which is, in part, a consequence of the common use of rodent models for preclinical validation of efficacy. Especially in the development of biologicals, which are now successfully used in the treatment of rheumatoid arthritis, the selection of the right animal model is pivotal. Non-human primates could help to bridge the evolutionary gap between rodent models and human patients.

Phagocytes containing a disease-promoting Toll-like receptor/Nod ligand are present in the brain during demyelinating disease in primates

Recent studies claim a central role for Toll-like receptor (TLR) ligands in stimulating autoimmune disease by activation of antigen-presenting cells in the target organ, but it is unclear if and how TLR ligands reach target organs. Most evidence comes from rodent models, and it is uncertain whether this principle holds in primates. Here we identify which cells contain peptidoglycan (PGN) in multiple sclerosis brain and in two nonhuman primate experimental autoimmune encephalomyelitis (EAE) models with different disease courses: acute (rhesus monkey) versus chronic disease (marmoset). Because persistence of TLR ligands in the central nervous system might be consequential for disease progression, we also determined the expression of two major PGN-degrading enzymes, ie, lysozyme and N-acetylmuramyl-l-alanine amidase. Distinct phagocyte subsets, including granulocytes, macrophages, and dendritic cells, contained PGN in the brain and coexpressed the inflammatory cytokine interleukin-12. The number of phagocytes carrying PGN increased in acute and chronic EAE compared with control animals, with the highest number of PGN-containing cells in acute EAE brain. Lytic enzymes were scarcely expressed in monkey and multiple sclerosis brain, favoring PGN persistence. PGN stimulated interleukin-12p70 release by leukocytes from all three primate species. The presence of PGN in the inflamed brain may have major implications because TLR2/Nod ligation potentially promotes inflammation and disease progression.

Modeling human arthritic diseases in nonhuman primates

Models of rheumatoid arthritis (RA) in laboratory animals are important tools for research into pathogenic mechanisms and the development of effective, safe therapies. Rodent models (rats and mice) have provided important information about the pathogenic mechanisms. However, the evolutionary distance between rodents and humans hampers the translation of scientific principles into effective therapies. The impact of the genetic distance between the species is especially seen with treatments based on biological molecules, which are usually species-specific. The outbred nature and the closer anatomical, genetic, microbiological, physiological, and immunological similarity of nonhuman primates to humans may help to bridge the wide gap between inbred rodent strain models and the heterogeneous RA patient population. Here we review clinical, immunological and pathological aspects of the rhesus monkey model of collagen-induced arthritis, which has emerged as a reproducible model of human RA in nonhuman primates.

Primate spondyloarthropathy

Spondyloarthropathy is a common occurrence in Old World primates, with only limited presence in New World monkeys. Clearly distinguished from rheumatoid arthritis, this erosive arthritis afflicts 20% of great apes, baboons, and rhesus macaques and had been increasing in frequency. Habitat-dependent infectious agent diarrhea-induced reactive arthritis is implicated on a background of genetic predisposition. A gorilla-derived therapeutic preventative approach has possible application in human clinical medicine.

Inhibition of the development of collagen-induced arthritis in rhesus monkeys by a small molecular weight antagonist of CCR5

OBJECTIVE

Collagen-induced arthritis (CIA) in the rhesus monkey is a nonhuman primate model of rheumatoid arthritis (RA). The close phylogenetic relationship between humans and the rhesus monkey makes this model useful for the preclinical safety and efficacy testing of new therapies that are inactive in animals more distinctly related to humans. In this study, we tested the therapeutic potential of a novel, small molecular weight antagonist of CCR5, SCH-X, in this model.

METHODS

CIA was induced in 10 rhesus monkeys. The animals were allocated to receive SCH-X or saline as the control (n = 5 in each group). Treatment was initiated on the day of CIA induction and continued for 45 days. Monkeys were monitored before and 63 days after CIA induction for macroscopic signs of clinical arthritis, such as soft-tissue swelling and body weight. Furthermore, markers of inflammation and joint degradation were monitored to follow the disease course.

RESULTS

Only 2 of 5 animals in the SCH-X-treated group displayed prominent soft-tissue swelling, compared with all 5 saline-treated monkeys. In addition to the suppression of joint inflammation, treatment with SCH-X resulted in a reduction in joint destruction, as demonstrated by lower rates of urinary excretion of collagen crosslinks, with confirmation by histology. Whereas in all saline-treated monkeys, marked erosion of joint cartilage was observed, this was absent in 4 of the 5 SCH-X-treated monkeys.

CONCLUSION

The systemic effects of treatment with SCH-X were a suppressed acute-phase reaction (reduction in C-reactive protein level) in the 3 treated monkeys with CIA that remained asymptomatic, and an altered antibody response toward type II collagen. The results suggest that the CCR5 antagonist SCH-X might have a strong clinical potential for treatment during periods of active inflammation, as seen in RA.

Genetic makeup of the DR region in rhesus macaques: gene content, transcripts, and pseudogenes

In the human population, five major HLA-DRB haplotypes have been identified, whereas the situation in rhesus macaques (Macaca mulatta) is radically different. At least 30 Mamu-DRB region configurations, displaying polymorphism with regard to number and combination of DRB loci present per haplotype, have been characterized. Until now, Mamu-DRB region genes have been studied mainly by genomic sequencing of polymorphic exon 2 segments. However, relatively little is known about the expression status of these genes. To understand which exon 2 segments may represent functional genes, full-length cDNA analyses of -DRA and -DRB were initiated. In the course of the study, 11 cDRA alleles were identified, representing four distinct gene products. Amino acid replacements are confined to the leader peptide and cytoplasmatic tail, whereas residues of the alpha1 domain involved in peptide binding, are conserved between humans, chimpanzees, and rhesus macaques. Furthermore, from the 11 Mamu-DRB region configurations present in this panel, 28 cDRB alleles were isolated, constituting 12 distinct cDRA/cDRB configurations. Evidence is presented that a single configuration expresses maximally up to three -DRB genes. For some exon 2 DRB sequences, the corresponding transcripts could not be detected, rendering such alleles as probable pseudogenes. The full-length cDRA and cDRB sequences are necessary to construct Mhc class II tetramers, as well as transfectant cell lines. As the rhesus macaque is an important animal model in AIDS vaccine studies, the information provided in this communication is essential to define restriction elements and to monitor immune responses in SIV/simian human immunodeficiency virus-infected rhesus macaques.

Gene therapy in nonhuman primate models of human autoimmune disease

Before autoimmune diseases in humans can be treated with gene therapy, the safety and efficacy of the used vectors must be tested in valid experimental models. Monkeys, such as the rhesus macaque or the common marmoset, provide such models. This publication reviews the state of the art in monkey models for rheumatoid arthritis and multiple sclerosis and the (few) gene therapy experiments that have been performed in these models.

Transfer of central nervous system autoantigens and presentation in secondary lymphoid organs

Dendritic cells are thought to regulate tolerance induction vs immunization by transferring Ags and peripheral signals to draining lymph nodes (LN). However, whether myelin Ag transfer and presentation in LN occurs during demyelinating brain disease is unknown. In this study, we demonstrate redistribution of autoantigens from brain lesions to cervical LN in monkey experimental autoimmune encephalomyelitis (EAE) and in multiple sclerosis (MS). Immunohistochemical analysis revealed significantly more cells containing myelin Ags in cervical LN of monkeys with EAE compared with those of healthy control monkeys. Myelin Ags were observed in cells expressing dendritic cell/macrophage-specific markers, MHC class II, and costimulatory molecules. Moreover, these cells were directly juxtaposed to T cells, suggesting that cognate interactions between myelin-containing APC and T cells are taking place in brain-draining LN. Indeed, myelin Ag-reactive T cells were observed in cervical LN from marmosets and rhesus monkeys. Importantly, these findings were paralleled by our findings in human tissue. We observed significantly more myelin Ag-containing cells in LN of individuals with MS compared with those of control individuals. These cells expressed APC markers, as observed in marmosets and rhesus monkeys. These findings suggest that during MS and EAE, modulation of T cell reactivity against brain-derived Ags also takes place in cervical LN and not necessarily inside the brain. A major implication is that novel therapeutic strategies may be targeted to peripheral events, thereby circumventing the blood-brain barrier.

Major histocompatibility complex class II polymorphisms in Macaca mulatta: factors influencing comprehensive genotyping of Macaca mulatta (Mamu)-DQA1 alleles by PCR-RFLP in archival samples

In the last 5 years, HLA class II genotyping methods have been adapted for genotyping of class II loci in rhesus macaques. Since previously published typing protocols were used on samples that were collected and stored under ideal conditions, it was of interest to determine if these methods were adequate for genotyping a large collection of archival samples from which DNA had been isolated and stored under various conditions. Established macaque DQA1 typing protocols were modified to optimize the typing procedure and enhance the ability to successfully genotype DNA from samples that were of poor quality and/or quantity. Long-term storage of whole-blood buffy coats or stored DNA extracted from whole-blood buffy coats did not affect typing success; however, amplification and typing of DNA extracted from archival samples of plasma were difficult and resulted in a low success rate. This suggests that amplification and DQA1-genotyping of archival samples is possible with a modified protocol, but is influenced by the age and source of the sample, and to a lesser extent, the method used to extract DNA from sample substrates.

Prophylactic and therapeutic effects of a humanized monoclonal antibody against the IL-2 receptor (DACLIZUMAB) on collagen-induced arthritis (CIA) in rhesus monkeys

CIA in the rhesus monkey is an autoimmune-based polyarthritis with inflammation and erosion of synovial joints that shares various features with human rheumatoid arthritis (RA). The close phylogenetic relationship between man and rhesus monkey makes the model very suitable for preclinical safety and efficacy testing of new therapeutics with exclusive reactivity in primates. In this study we have investigated the prophylactic and therapeutic effects of a humanized monoclonal antibody (Daclizumab) against the alpha-chain of the IL-2 receptor (CD25). When Daclizumab treatment was started well after immunization but before the expected onset of CIA a significant reduction of joint-inflammation and joint-erosion was observed. A therapeutic treatment, initiated as soon as the first clinical signs of CIA were observed, proved also effective since joint-degradation was abrogated. The results of this study indicate that Daclizumab has clinical potential for the treatment of RA during periods of active inflammation and suppression of the destruction of the joint tissues.

Six mamu-A locus alleles defined by a polymerase chain reaction sequence specific primer method

Rhesus monkeys are relevant models for human diseases and transplantation. In each case, a complete understanding of these models requires knowledge of macaque MHC. Due to high polymorphism and multiple genes per haplotype, it has been difficult to develop a rapid typing method for rhesus monkey MHC class I. We developed a simple and rapid PCR-SSP strategy for rhesus monkey Mamu-A locus typing. Fifty-two rhesus monkeys were included in the study. Six rhesus monkey allel-specific primer pairs were designed based on published Mamu-A locus gene sequences. Allele-specific PCR products ranged in size from 346 to 788 bp; 5' and 3' Mamu-A locus allele specific primers were located in the second and third exons, respectively. Specific PCR product gel purification was followed by direct sequencing, without subcloning, in both directions. Our data showed variability in the number of Mamu-A alleles ranging from 1 to 4 per genotype. The highest frequencies were observed for Mamu-A*02, -A*04, and -A*03 alleles. Thus, we report here the first PCR-SSP typing method for Mamu-A*02, -03, -04, -05, -06, and -07 array of class I alleles. This technique appears to be a highly reproducible and discriminatory method for detecting this subset of class I A locus genes in rhesus monkeys.

Allelic diversity of Mhc-DRB alleles in rhesus macaques

The Biomedical Primate Research Centre (BPRC) rhesus macaque colony was started with a large number of wild-caught animals originating mainly from the Indian subcontinent. The contemporary self-sustaining colony comprises approximately 800 individuals. We screened a large section of the colony for Mamu-DRB polymorphisms by applying the denaturing gradient gel electrophoresis (DGGE) technique. Based on disparate DGGE profiles, animals were selected for nucleotide sequence analysis. This approach allowed the detection of 25 unreported Mamu-DRB alleles, bringing to 126 the total number of alleles documented in the literature. This communication demonstrates that rhesus macaques, like humans, display extensive allelic polymorphism at the DRB region. Phylogenetic analyses illustrate that humans and rhesus macaques share several Mhc-DRB loci and lineages. Identical exon 2 sequences, however, which are shared between humans and rhesus macaques, were not observed. This indicates that most primate Mhc-DRB alleles are of post-speciation origin.

Unprecedented polymorphism of Mhc-DRB region configurations in rhesus macaques

The rhesus macaque is an important model in preclinical transplantation research and for the study of chronic and infectious diseases, and so extensive knowledge of its MHC (MhcMamu) is needed. Nucleotide sequencing of exon 2 allowed the detection of 68 Mamu-DRB alleles. Although most alleles belong to loci/lineages that have human equivalents, identical Mhc-DRB alleles are not shared between humans and rhesus macaques. The number of -DRB genes present per haplotype can vary from two to seven in the rhesus macaque, whereas it ranges from one to four in humans. Within a panel of 210 rhesus macaques, 24 Mamu-DRB region configurations can be distinguished differing in the number and composition of loci. None of the Mamu-DRB region configurations has been described for any other species, and only one of them displays major allelic variation giving rise to a total of 33 Mamu-DRB haplotypes. In the human population, only five HLA-DRB region configurations were defined, which in contrast to the rhesus macaque exhibit extensive allelic polymorphism. In comparison with humans, the unprecedented polymorphism of the Mamu-DRB region configurations may reflect an alternative strategy of this primate species to cope with pathogens. Because of the Mamu-DRB diversity, nonhuman primate colonies used for immunological research should be thoroughly typed to facilitate proper interpretation of results. This approach will minimize as well the number of animals necessary to conduct experiments.

Identification of DRB alleles in rhesus monkeys using polymerase chain reaction-sequence-specific primers (PCR-SSP) amplification

Major histocompatibility complex (MHC) class In molecules play a vital role in the regulation of T-cell functions in the mammalian immune system. Two key features characterize the polymorphism of MHC haplotypes in humans and non-human primates: the existence of a large number of alleles, and the high degree of genetic diversity between those alleles. Rhesus monkeys and Chimpanzees have been extensively used as relevant models for human diseases and transplantation We have investigated DRB genes in 19 macaques, members of 3 families, using polymerase chain reaction with sequence-specific primers (PCR-SSP) and denaturing gradient gel electrophoresis (DGGE). After amplification PCR products were purified and subjected direct sequencing. Seven animals (Madison #1) were typed by DDGE also. We report that the DRB haplotypes defined by PCR-SSP exhibit a high degree of concordance with the data obtained by DGGE and direct sequening. Our data show prominent variability in the number of DRB1 alleles ranging from 1-4 per genotype within these families. This analysis demonstrated that most of the amplicons were identical to Mamu-DRB alleles that our PCR primers were to amplify. However, 98-99% similarity was noticed in the case of Mamu-DRB1*0303, Mamu-DRB6*0103 and Mamu-DRB*W201 alleles. The observed mismatches were located in non-polymorphic regions. Thus, family studies in rhesus macaques performed by molecular methods confirmed the multiplicity of Mamu-DRB1 alleles per haplotype and the existence of allelic associations published earlier. In addition, we propose 3 more DRB allele associations (haplotypes): Mamu-DRB1*04-DRB5*03; Mamu-DRB1*04-*DRB*W5; Mamu-DRB1*04*W2. The proposed medium-resolution PCR-SSP technique appears to be a highly reproducible and discriminatory typing method for detecting polymorphisms of DRB genes in rhesus monkeys.

DQ-haplotype analysis in rhesus macaques: implications for the evolution of these genes

The DQA1 and DQB1 alleles of 258 rhesus monkeys (Macaca mulatta) of different origin were typed by PCR-RFLP. Five novel MamuDQA1 and five novel -DQB1 alleles were detected and 15 Mamu-DQA1-DQB1 haplotypes were identified. Haplotype analysis confirmed the conservation of the DQA1*01-DQB1 *06 haplotypes in evolution. The most conspicuous finding was the tight linkage between the Mamu-DQA1 and -DQB1 alleles. Almost in every case the Mamu-DQA1 allele was linked to only one particular Mamu-DQB1 allele. Although there also are constraints in the formation of DQ haplotypes in humans, such tight linkages are not observed. These findings support the hypothesis of some kind of co-evolution between DQA1 and DQB1 alleles and may reflect a stronger force of natural selection in macaques than in humans.

Asymptomatic synovitis precedes clinically manifest arthritis

OBJECTIVE

It has been hypothesized that asymptomatic synovitis may precede clinical manifestations of arthritis in the earliest phase of rheumatoid arthritis (RA). To obtain more insight into this disease phase, we investigated the immunohistologic features of synovial tissue (ST) from the knee joints of rhesus monkeys with induced arthritis and from RA patients with both clinically involved and clinically uninvolved knee joints.

METHODS

Serial ST biopsy specimens from the knee joints of 4 rhesus monkeys that had been immunized with type II collagen and ST from 10 RA patients were investigated. Eight patients without inflammatory joint disease served as controls.

RESULTS

In ST from immunized monkeys, an influx of macrophages was observed well before the occurrence of arthritis. Signs of inflammation were also demonstrated in ST from clinically uninvolved knee joints of all RA patients evaluated. The ST was characterized in particular by infiltration with macrophages and by the expression of macrophage-derived cytokines.

CONCLUSION

The findings support the view that asymptomatic synovitis precedes clinically manifest arthritis in both early and established RA. This implies that the debut of RA already represents a chronic phase of the disease.

Collagen-induced arthritis in nonhuman primates: multiple epitopes of type II collagen can induce autoimmune-mediated arthritis in outbred cynomolgus monkeys

OBJECTIVE

To define which regions of the type II collagen (CII) molecule result in anticollagen antibody production and the subsequent development of autoantibodies in a collagen-induced arthritis (CIA) nonhuman primate model.

METHODS

Male and female cynomolgus monkeys (2-6 of each sex per group) were immunized with either chicken (Ch), human, or monkey (Mk) CII, or with cyanogen bromide (CB)-generated peptide fragments of ChCII emulsified in Freund's complete adjuvant. Monkeys were observed for the development of arthritis, and sera were collected and analyzed for anticollagen antibody specificity by enzyme-linked immunosorbent assay.

RESULTS

Overt arthritis developed in all groups of monkeys immunized with intact CII and with all major CB peptide fragments of ChCII except CB8. Onset and severity of arthritis correlated best with serum anti-MkCII antibody levels. The levels of IgG autoantibody to MkCII were a result of the cross-reactivity rate of anti-heterologous CII antibodies with MkCII, which was based on the genetic background of individual monkeys rather than on sex differences.

CONCLUSION

CII from several species and disparate regions of the CII molecule were able to induce autoantibody-mediated arthritis in outbred cynomolgus monkeys. The strong anti-MkCII response suggests that epitope spreading or induction of broad-based CII cross-reactivity occurred in these animals. Autoantibody levels to MkCII were higher in CIA-susceptible monkeys than in resistant monkeys, despite comparable antibody levels in response to the various immunizations of CII. These results closely parallel the type of anticollagen responses found in sera from rheumatoid arthritis patients. Perhaps this can be accounted for by similar major histocompatibility complex heterogenicity associated with an outbred population, or maybe this is a primate-specific pattern of reactivity to CII.

Growth transformation of antigen-specific T cell lines from rhesus monkeys by herpesvirus saimiri

This study aims in establishing the in vitro basis for a primate model to evaluate potential applications of H. saimiri-transformed T cells. T cell lines specific for myelin basic protein and streptolysin O were derived from rhesus monkeys and transformed to stable antigen-independent growth with strain C488 of H. saimiri. The transformed T cells from rhesus monkeys did not produce infectious virus and harbored the H. saimiri genome exclusively in an episomal form, whereas transformed T cells from the New World monkey Calltithrix jacchus released infectious virus. Transformed T cells from rhesus monkeys showed an unaltered surface expression of CD2 and CD3, of the activation markers CD25 and CD69, and of the costimulatory molecule CD80 (B7.1). Remarkably, both transformed and nontransformed T cell lines were largely double-positive for CD4 and CD8. In contrast to the parental cell lines, the transformed cells constitutively expressed major histocompatibility complex-DR antigens and were able to present antigen to each other. The transformed T cells from rhesus monkeys continued to express a functionally intact T cell receptor and responded to recognition of their antigen with enhanced proliferation and production of Th1-type cytokines. In conclusion, H. saimiri-transformed rhesus monkey T cells may open a way to primate models for adoptive immunotherapy and studies on the pathogenesis of autoaggressive T cells.

PCR-RFLP-based Mamu-DQB1 typing of rhesus monkeys: characterization of two novel alleles

Up to now 19 allelic sequences of the rhesus monkey DQB1 locus have been published. Referring to these sequences, we have developed a typing protocol for Mamu-DQB1 alleles which was verified by additional cloning, sequence analysis and segregation studies. The protocol is based on the amplification of the second exon with only one specific primer pair followed by the digestion of the PCR products with up to 10 different restriction endonucleases. The alleles can be identified in homozygous and heterozygous combinations since most amplified second exon sequences give unique hand patterns after digestion with at least one of the selected restriction endonucleases. By the use of this protocol we analyzed DNA-samples from 182 rhesus monkeys. Among these samples two novel Mamu-DQB1 alleles were detected, subsequently cloned and their nucleic sequence determined. Since we typed four complete breeding groups consisting of two generations we were able to identify several DQ haplotypes by segregation analysis using the previously developed typing protocol for DQA1.

Characterization of the natural immune response of rhesus monkey CD4+ve T cells to the bacterial antigen streptolysin O (SLO)

Rhesus monkeys show a high proliferative T cell response to the bacterial exotoxin SLO without prior immunization. The present study was undertaken to characterize this naturally present SLO-responsiveness with particular emphasis on CD4+ve reactive T cells. It is demonstrated that the frequency of SLO-reactive cells in the circulation.ranges between 1 in 75 and 1 in 610 CD4+ve T cells as determined with limiting dilution analysis. It is also shown that induction of a good proliferative response requires Mhc-DR matching between T cell and the antigen presenting cells (APC). Stable and DR-restricted SLO-specific CD4+ve T cell lines were generated from CD8 depleted peripheral blood mononuclear cells (PBMC). The SLO-reactive CD4+ve cell lines are tentatively characterized as Th1-like based on the predominant production of interferon-gamma (IFN-gamma) over IL-4, although this seems contradicted by the IL-4 dependent growth of the lines.

Structure and diversity of the T-cell receptor alpha chain in rhesus macaque and chimpanzee

We cloned and sequenced cDNA for the TCRAC1 of a healthy rhesus monkey and chimpanzee. TCRAC1 from both nonhuman primates show extensive conservation compared to the human sequence and to other mammals. A possible primate-specific insertion near the hinge region of the TCRAC1 region is described. Characterization of 18 rhesus macaque and eight chimpanzee TCRA chain cDNA clones derived from inverse PCR revealed 12 different TCRAV and 16 different TCRAJ regions which corresponded closely to known human counterparts. One functional rhesus macaque TCRDV-TCRAJ rearrangement was detected, suggesting a genomic organization of the macaque TCRD locus which is similar to humans. At the genomic level, a single TCRAC1 gene segment was detected in rhesus macaque and chimpanzee. The close phylogenetic relationship between primates shown here for TCRA chain components supports the use of these species as animal models of human immune-mediated disease.

Biochemical and molecular characterization of rhesus monkey major histocompatibility complex class II DR

Rapid, simple techniques for MHC class II typing were explored to facilitate the use of a wide variety of nonhuman primate species as models of human diseases and therapies. We demonstrate that radioimmunoprecipitation and 1-D IEF or 1-D NEPHGE can be employed for characterizing MHC class II DR alleles in rhesus monkeys. Complementary molecular analyses have yielded the first full-length nonhuman primate DRA sequence and the first full-length rhesus macaque DRB sequences. In this way it has also been possible to determine which subset of the DRB sequences amplified from a B-LCL are actually expressed.