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Results for “Immunity, Innate”

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PubMed2002

Flagellin perception: a paradigm for innate immunity.

There are surprising similarities between how animals and plants perceive pathogens. In animals, innate immunity is based on the recognition of pathogen-associated molecular patterns. This is mediated by the Toll-like receptor (TLR) family, which rapidly induce the innate immunity response, a first line of defence against infectious disease. Plants have highly sensitive perception systems for general elicitors and they respond to these stimuli with a defence response. One of these general elicitors is flagellin, the main component of the bacterial flagellum. Genetic analysis in Arabidopsis has shown that FLS2, which encodes a receptor-like kinase, is essential for flagellin perception. FLS2 shares homology with the TLR family, and TLR5 is responsible for flagellin perception in mammals.

Animals↗

PubMed2006

Is inflammaging an auto[innate]immunity subclinical syndrome?

The low-grade, chronic, systemic inflammatory state that characterizes the aging process (inflammaging) results from late evolutive-based expression of the innate immune system. Inflammaging is characterized by the complex set of five conditions which can be described as 1. low-grade, 2. controlled, 3. asymptomatic, 4. chronic, 5. systemic, inflammatory state, and fits with the antagonistic pleiotropy theory on the evolution of aging postulating that senescence is the late deleterious effect of genes (pro-inflammatory versus anti-inflammatory) that are beneficial in early life. Evolutionary programming of the innate immune system may act via selection on these genetic traits. Here I propose that the already acquired knowledge in this field may pave the way to a new chapter in the pathophysiology of autoimmunity: the auto-innate-immunity syndromes. Indeed, differently from the well known chapter of conventional autoimmune diseases and syndromes where the main actor is the adaptive immunity, inflammaging may constitute the subclinical paradigm of a new chapter of autoimmunity, namely that arising from an autoimmune inflammatory response of the innate-immune-system, an old actor of immunity and yet a new actor of autoimmunity, also acting as a major determinant of elderly frailty and age-associated diseases.

Journal Article↗

PubMed2007

Protection of the neonate by the innate immune system of developing gut and of human milk.

The neonatal adaptive immune system, relatively naïve to foreign antigens, requires synergy with the innate immune system to protect the intestine. Goblet cells provide mucins, Paneth cells produce antimicrobial peptides, and dendritic cells (DCs) present luminal antigens. Intracellular signaling by Toll-like receptors (TLRs) elicits chemokines and cytokines that modulate inflammation. Enteric neurons and lymphocytes provide paracrine and endocrine signaling. However, full protection requires human milk. Breast-feeding reduces enteric infection and may reduce chronic disease in later life. Although human milk contains significant secretory immunoglobulin A (sIgA), most of its protective factors are constitutively expressed. Multifunctional milk components are nutrients whose partial digestion products inhibit pathogens. Cytokines, cytokine receptors, TLR agonists and antagonists, hormones, anti-inflammatory agents, and nucleotides in milk modulate inflammation. Human milk is rich in glycans (complex carbohydrates): As prebiotics, indigestible glycans stimulate colonization by probiotic organisms, modulating mucosal immunity and protecting against pathogens. Through structural homology to intestinal cell surface receptors, glycans inhibit pathogen binding, the essential first step of pathogenesis. Bioactive milk components comprise an innate immune system of human milk whereby the mother protects her nursing infant. Interactions between human milk glycans, intestinal microflora, and intestinal mucosa surface glycans underlie ontogeny of innate mucosal immunity, pathobiology of enteric infection, and inflammatory bowel diseases.

Gastrointestinal Tract↗

PubMed2003

Modulation of the innate immune response by NMDA receptors has neuropathological consequences.

The aim of this study was to determine whether glutamate receptors modulate the innate immune response in the brain of C3H/HeN and C3H/HeJ mice; the latter bear a loss of function in the toll-like receptor (TLR) 4 gene. Mice received an intrastriatal (IS) infusion of lipopolysaccharide (LPS), the exogenous ligand for TLR4, and were killed at several times thereafter. This treatment activated the transcription of a wide variety of genes involved in the control of the innate immune response. MK-801, an antagonist of NMDA glutamate receptor subtype, exacerbated the effects of the endotoxin in the brain of C3H/HeN mice but not in TLR4-deficient animals. The ipsilateral side of C3H/HeN mice exhibited stronger hybridization signals for the mRNA encoding TLR2, CD14, tumor necrosis factor-alpha, and inhibitory factor-kappaBalpha at various times after the treatment combining MK-801 and LPS. This robust inflammatory response in the brain of C3H/HeN mice was not associated with any convincing signs of neurodegeneration or demyelination that was verified via numerous approaches and at time up to 2 weeks after injection. However, animals that received long-term IS infusion of LPS, together with MK-801, exhibited a significant increase in demyelination levels within the ipsilateral side. Our results demonstrate that binding of glutamate to its cognate NMDA receptor modulates LPS-induced innate immune reaction in a TLR4-dependent manner. This acute response may be crucial to eliminate bacterial cell wall components and minimizing tissue injury. However, sustained deregulation of proinflammatory signaling involving NMDA receptors leads to demyelination and is likely to be a mechanism participating in such pathological conditions.

Animals↗

PubMed2005

Genetic analysis of innate immunity: identification and function of the TIR adapter proteins.

The innate immune system senses pathogens largely through signals initiated by a collection of phylogenetically related proteins known as "Toll-like receptors" (TLRs), of which ten representatives are encoded in the human genome. The sensing role of the TLRs first came to light when one member of this family, TLR4, was shown to serve the detection of endotoxin (lipopolysaccharide; LPS) in mice. This discovery was based upon positional cloning of a spontaneous mutation affecting a locus known as Lps. The recognition specificities of other TLRs have since been established by reverse genetic methods. The understanding of the biochemical circuitry that maintains the innate capacity for immune recognition and response has loomed as the next hurdle in the field. A total of five adapter proteins with cytoplasmic domain homology to the TLRs are known to exist in mammals. These proteins are not entirely promiscuous in their interaction with TLRs, but rather, show preferential association with individual family members, giving a particular character to the signals that distinct micro-organisms initiate. The adaptive immune response is dependent upon upregulation of costimulatory molecules (UCM) such as CD80 and CD86. Very recently, it has been shown that this upregulation is dependent upon an adapter encoded by a locus known as Lps2, known as Trif or Ticam-1, and upon type I interferon receptor signaling. LPS and dsRNA both signal via Trif, but dsRNA has an accessory pathway for UCM, that is independent of both Trif/Ticam-1 and the known dsRNA receptor, TLR3. Other key innate immunity genes have also been disclosed by germline mutagenesis, and are discussed in the present review.

Adaptor Proteins, Signal Transducing↗

PubMed2026

Conserved innate immunity components limit transgene expression in adult planarians.

The planarian flatworm Schmidtea mediterranea has become a powerful model for studying whole-body regeneration, tissue patterning, and stem cell regulation. Yet the absence of reliable tools for transgene expression still limits the elucidation of molecular mechanisms in in this system. Here, we establish a proof-of-principle system for plasmid-based expression of NanoLuciferase (NanoLuc) in S. mediterranea, employing commercially available transfection reagents and a panel of endogenous promoter sequences. Despite successful delivery, reporter expression remained low and transient. To identify biological barriers to robust transgene expression, we investigated the role of innate immune pathways. Candidate gene searches and biochemical pull-down of cytoplasmic DNA coupled to mass spectrometry identified several planarian homologs of conserved immune regulators and putative DNA sensors. Through RNA interference screening of conserved innate immune components, we uncover roles for S. mediterranea homologs of Tank-binding kinase 1 (TBK1) and macrophage mannose receptor 1 (MRC1) as potent repressors of transgene expression. Transcriptomic and functional analyses further implicate TBK1 in regulating broad innate immune and stress-response programs, akin to its vertebrate function. Together, our findings demonstrate that innate immune signaling limits transgene expression in S. mediterranea and suggest that modulating these pathways may be key to enabling stable and efficient genetic manipulation in planarians.

Animals↗

PubMed2004

Innate immunity and toll-like receptors: clinical implications of basic science research.

Humans are constantly exposed to a wide variety of microorganisms that can cause infection. In self-defense, the human host has evolved complex protective mechanisms, and Toll-like receptors (TLRs) have emerged as a central point in defense. These receptors bind molecular structures that are expressed by microbes but are not expressed by the human host, eg, lipopolysaccharides (LPS) or double-stranded RNA (dsRNA). Activation of these receptors initiates an inflammatory cascade that attempts to clear the offending pathogen and set in motion a specific adaptive immune response. Defects in sensing of pathogens may predispose the host to recurrent infections. The relative rarity of these syndromes of defective innate immunity, however, speaks to the redundancy in sensing of pathogens by the innate immune system. More common, polymorphisms in TLR4 are associated with increased predisposition to severe and recurrent infections but protection against atherosclerotic disease due to diminished inflammation. Toll-like receptor signaling may also contribute to the pathophysiology of disease and injure the host by activating a deleterious immune response such as in sepsis or inflammatory bowel disease (IBD). The focus of this article is to describe the role of TLRs in the innate immune response in health and disease.

Humans↗

PubMed2005

Unraveling innate immunity using large scale N-ethyl-N-nitrosourea mutagenesis.

With the mouse genome almost entirely sequenced and readily accessible to all who wish to examine it, the challenge across most biological disciplines now lies in the decipherment of gene and protein function rather than in the realm of gene identification per se. In the field of innate immunity, forward genetic methods have repeatedly been applied to identify key sensors, adapters, and effector molecules. However, most spontaneous mutations that affect innate immune function have been mapped and cloned, and the need for new monogenic phenotypes has been felt evermore keenly. N-Ethyl-N-nitrosourea (ENU) mutagenesis is an efficient tool for the creation of aberrant monogenic innate immune response phenotypes. In this review, we will discuss the potential of the forward genetic approach and ENU mutagenesis to identify new genes and new functions of known genes related to innate immunity.

Adaptor Proteins, Signal Transducing↗

PubMed2006

Lymphocytes are detrimental during the early innate immune response against Listeria monocytogenes.

Mice deficient in lymphocytes are more resistant than normal mice to Listeria monocytogenes infection during the early innate immune response. This paradox remains unresolved: lymphocytes are required for sterilizing immunity, but their presence during the early stage of the infection is not an asset and may even be detrimental. We found that lymphocyte-deficient mice, which showed limited apoptosis in infected organs, were resistant during the first four days of infection but became susceptible when engrafted with lymphocytes. Engraftment with lymphocytes from type I interferon receptor-deficient (IFN-alphabetaR(-/-)) mice, which had reduced apoptosis, did not confer increased susceptibility to infection, even when the phagocytes were IFN-alphabetaR(+/+). The attenuation of innate immunity was due, in part, to the production of the antiinflammatory cytokine interleukin 10 by phagocytic cells after the apoptotic phase of the infection. Thus, immunodeficient mice were more resistant relative to normal mice because the latter went through a stage of lymphocyte apoptosis that was detrimental to the innate immune response. This is an example of a bacterial pathogen creating a cascade of events that leads to a permissive infective niche early during infection.

Animals↗

PubMed2006

Multi-directional cross-regulation of NK cell function during innate immune responses.

In recent years a number of studies allowed major advances in our understanding of different cell types of the innate immunity and of the role they play during the early phases of infections. Some of these cells, such as mast cells, endothelial cells and certain immature dendritic cells (iDCs), are resident within peripheral tissues, while others, including NK cells, are rapidly recruited from blood stream. These studies indicated that innate immunity cells interact each other in inflamed tissues and in secondary lymphoid organs leading to modulation or amplification of different innate effector mechanisms and that a large array of microbial products can directly activate different effector cells of the innate immunity, also including NK cells. The final outcome of these cellular interactions may have dramatic impact on the quality and strength of down-stream adaptive immune responses. Noticeably, the effect on the adaptive immunity can result not only from the action of polarizing cytokines such as IL12 or IL4, but also from the NK-mediated "DC editing" leading to the selection of the most suitable DCs for subsequent priming of Th1 cell responses. Thus classical innate effector cells can also be viewed as regulatory cells that play a pivotal role in defenses against pathogens.

Cytokines↗

PubMed2003

Innate immune defences in the human endometrium.

The human endometrium is an important site of innate immune defence, giving protection against uterine infection. Such protection is critical to successful implantation and pregnancy. Infection is a major cause of preterm birth and can also cause infertility and ectopic pregnancy. Natural anti-microbial peptides are key mediators of the innate immune system. These peptides, between them, have anti-bacterial, anti-fungal and anti-viral activity and are expressed at epithelial surfaces throughout the female genital tract. Two families of natural anti-microbials, the defensins and the whey acidic protein (WAP) motif proteins, appear to be prominent in endometrium. The human endometrial epithelium expresses beta-defensins 1-4 and the WAP motif protein, secretory leukocyte protease inhibitor. Each beta-defensin has a different expression profile in relation to the stage of the menstrual cycle, providing potential protection throughout the cycle. Secretory leukocyte protease inhibitor is expressed during the secretory phase of the cycle and has a range of possible roles including anti-protease and anti-microbial activity as well as having effects on epithelial cell growth. The leukocyte populations in the endometrium are also a source of anti-microbial production. Neutrophils are a particularly rich source of alpha-defensins, lactoferrin, lysozyme and the WAP motif protein, elafin. The presence of neutrophils during menstruation will enhance anti-microbial protection at a time when the epithelial barrier is disrupted. Several other anti-microbials including the natural killer cell product, granulysin, are likely to have a role in endometrium. The sequential production of natural anti-microbial peptides by the endometrium throughout the menstrual cycle and at other sites in the female genital tract will offer protection from many pathogens, including those that are sexually transmitted.

Antimicrobial Cationic Peptides↗

PubMed2001

The 2.0-A crystal structure of tachylectin 5A provides evidence for the common origin of the innate immunity and the blood coagulation systems.

Because invertebrates lack an adaptive immune system, they had to evolve effective intrinsic defense strategies against a variety of microbial pathogens. This ancient form of host defense, the innate immunity, is present in all multicellular organisms including humans. The innate immune system of the Japanese horseshoe crab Tachypleus tridentatus, serving as a model organism, includes a hemolymph coagulation system, which participates both in defense against microbes and in hemostasis. Early work on the evolution of vertebrate fibrinogen suggested a common origin of the arthropod hemolymph coagulation and the vertebrate blood coagulation systems. However, this conjecture could not be verified by comparing the structures of coagulogen, the clotting protein of the horseshoe crab, and of mammalian fibrinogen. Here we report the crystal structure of tachylectin 5A (TL5A), a nonself-recognizing lectin from the hemolymph plasma of T. tridentatus. TL5A shares not only a common fold but also related functional sites with the gamma fragment of mammalian fibrinogen. Our observations provide the first structural evidence of a common ancestor for the innate immunity and the blood coagulation systems.

Amino Acid Sequence↗

PubMed2004

Innate immunity of the sinonasal cavity: expression of messenger RNA for complement cascade components and toll-like receptors.

OBJECTIVE: To study the expression of important elements of the innate immune responses in human sinonasal tissue to elucidate its potential role in mucosal inflammation. DESIGN: We studied human sinonasal tissue from patients with chronic rhinosinusitis and an immortalized epithelial cell line to detect the expression of innate immune effectors and the responses of these cells to stimulation with compounds associated with pathogenic organisms. PATIENTS: Nine individuals undergoing endoscopic sinus surgery for chronic rhinosinusitis. MAIN OUTCOME MEASURES: Expression of complement components and toll-like receptors. RESULTS: We found detectable levels of messenger RNA for all toll-like receptors in human sinonasal tissue and in the BEAS-2B epithelial cell line. Expression of several components of the alternate pathway of complement (factors B, H, and I and properdin) was constitutively present in unstimulated BEAS-2B cells and was readily detectable in human sinonasal tissue. Stimulation of BEAS-2B cells with the toll-like receptor 3 ligand double-stranded RNA resulted in increased expression of messenger RNA for factors B and H but not for properdin or factor I. CONCLUSIONS: Toll-like receptors and the alternate pathway of complement are important components of innate immunity that are expressed in human sinonasal epithelium in vivo and in cultured airway epithelial cells in vitro. The expression of some of these components can be significantly induced by stimulation via toll-like receptors, and epithelial expression of components of innate immunity may play a role in inflammation in chronic rhinosinusitis.

Cells, Cultured↗

PubMed2006

Macrophage inflammatory protein 3alpha deficiency in atopic dermatitis skin and role in innate immune response to vaccinia virus.

BACKGROUND: Patients with atopic dermatitis (AD) are prone to disseminated viral skin infections and therefore are not vaccinated against smallpox because of potential complications. Macrophage inflammatory protein 3alpha (MIP-3alpha) is a C-C chemokine expressed by keratinocytes that exhibits antimicrobial activity against bacteria and fungi; however, its role in antiviral innate immunity is unknown. OBJECTIVE: Evaluate the level of MIP-3alpha in AD skin and its role in the innate immune response to vaccinia virus (VV). METHODS: Macrophage inflammatory protein 3alpha levels were evaluated using real-time RT-PCR, immunodot-blot, and immunohistochemistry. The antiviral activity of MIP-3alpha was determined using a standard viral plaque assay. RESULTS: Macrophage inflammatory protein 3alpha gene expression was significantly (P < .01) decreased in AD skin (0.21 +/- 0.05 ng MIP-3alpha/ng glyceraldehyde-3-phosphate dehydrogenase) compared with psoriasis skin (0.67 +/- 0.13). This was confirmed at the protein level using immunohistochemistry. We further demonstrate that T(H)2 cytokines downregulate MIP-3alpha expression. The importance of MIP-3alpha in the innate immune response against VV was established by first demonstrating that MIP-3alpha exhibits activity against VV. Second, VV replication was significantly increased (P < .01) in keratinocytes treated with an antibody to neutralize MIP-3alpha. CONCLUSION: The current study demonstrates that MIP-3alpha exhibits antiviral activity against VV and demonstrates the importance of MIP-3alpha in the innate immune response against VV. In addition, AD skin is deficient in MIP-3alpha, in part because of the overexpression of T(H)2 cytokines in AD skin. CLINICAL IMPLICATIONS: MIP-3alpha deficiency in AD skin contributes to patients' increased propensity toward eczema vaccinatum. Increasing MIP-3alpha or neutralizing T(H)2 cytokines could prevent adverse reactions in patients with AD after smallpox vaccination.

Adult↗

PubMed2005

Dysregulated innate immune responses in young children with autism spectrum disorders: their relationship to gastrointestinal symptoms and dietary intervention.

OBJECTIVE: Our previous study indicated an association between cellular immune reactivity to common dietary proteins (DPs) and excessive proinflammatory cytokine production with endotoxin (lipopolysaccharide, LPS), a major stimulant of innate immunity in the gut mucosa, in a subset of autism spectrum disorder (ASD) children. However, it is unclear whether such abnormal LPS responses are intrinsic in these ASD children or the results of chronic gastrointestinal (GI) inflammation secondary to immune reactivity to DPs. This study further explored possible dysregulated production of proinflammatory and counter-regulatory cytokines with LPS in ASD children and its relationship to GI symptoms and the effects of dietary intervention measures. METHODS: This study includes ASD children (median age 4.8 years) on the unrestricted (n = 100) or elimination (n = 77) diet appropriate with their immune reactivity. Controls include children with non-allergic food hypersensitivity (NFH; median age 2.9 years) on the unrestricted (n = 14) or elimination (n = 16) diet, and typically developing children (median age 4.5 years, n = 13). The innate immune responses were assessed by measuring production of proinflammatory (TNF-alpha, IL-1beta, IL-6, and IL-12) and counter-regulatory (IL-1ra, IL-10, and sTNFRII) cytokines by peripheral blood mononuclear cells (PBMCs) with LPS. The results were also compared to T-cell responses with common DPs and control T-cell mitogens assessed by measuring T-cell cytokine production. RESULTS: ASD and NFH PBMCs produced higher levels of TNF-alpha with LPS than controls regardless of dietary interventions. However, only in PBMCs from ASD children with positive gastrointestinal (GI(+)) symptoms, did we find a positive association between TNF-alpha levels produced with LPS and those with cow's milk protein (CMP) and its major components regardless of dietary interventions. In the unrestricted diet group, GI(+) ASD PBMCs produced higher IL-12 than controls and less IL-10 than GI(-) ASD PBMCs with LPS. GI(+) ASD but not GI(-) ASD or NFH PBMCs produced less counter-regulatory cytokines with LPS in the unrestricted diet group than in the elimination diet group. There was no significant difference among the study groups with regard to cytokine production in responses to T-cell mitogens and other recall antigens. CONCLUSION: Our results revealed that there are findings limited to GI(+) ASD PBMCs in both the unrestricted and elimination diet groups. Thus our findings indicate intrinsic defects of innate immune responses in GI(+) ASD children but not in NFH or GI(-) ASD children, suggesting a possible link between GI and behavioral symptoms mediated by innate immune abnormalities.

Autistic Disorder↗

PubMed2002

Differential activation of innate immune responses by adenovirus and adeno-associated virus vectors.

Adenovirus vectors induce acute inflammation of infected tissues due to activation of the innate immune system and expression of numerous chemokines and cytokines in transduced target cells. In contrast, adeno-associated virus (AAV) vectors are not associated with significant inflammation experimentally or clinically. We tested the ability of AAV vectors to induce the expression of chemokines in vitro and to activate the innate immune system in vivo. In human HeLa cells and murine renal epithelium-derived cells (REC cells) the adenovirus vector AdlacZ induced the expression of multiple inflammatory chemokines including RANTES, interferon-inducible protein 10 (IP-10), interleukin-8 (IL-8), MIP-1beta, and MIP-2 in a dose-dependent manner. The use of AAVlacZ did not induce the expression of these chemokines above baseline levels despite 40-fold-greater titers than AdlacZ and greater amounts of intracellular AAVlacZ genomes according to Southern and slot blot analysis. This finding confirmed that the lack of AAVlacZ induction of chemokine was not due to reduced transduction. In DBA/2 mice, the intravenous administration of 2.5 x 10(11) particles of AAVlacZ resulted in the rapid induction of liver tumor necrosis factor alpha (TNF-alpha), RANTES, IP-10, MIP-1beta, MCP-1, and MIP-2 mRNAs. However, 6 h following injection, chemokine mRNA levels returned to baseline. As expected, administration of 10-fold less AdlacZ caused an induction of liver TNF-alpha and chemokine mRNAs that persisted for more than 24 h posttransduction. Whereas intravenous administration of 2.5 x 10(11) particles of AAVlacZ triggered a transient infiltration of neutrophils and CD11b(+) cells into liver, this response stood in contrast to widespread inflammation and toxicity induced by AdlacZ. Kupffer cell depletion abolished AAVlacZ but not AdlacZ-induced chemokine expression and neutrophil infiltration. In summary, these results show that AAV vectors activate the innate immune system to a lesser extent than do adenovirus vectors and offer a possible explanation for the reduced inflammatory properties of AAV compared to adenovirus vectors.

Adenoviruses, Human↗

PubMed2001

Tehao functions in the Toll pathway in Drosophila melanogaster: possible roles in development and innate immunity.

Toll and related proteins play important roles in innate immunity in both invertebrates and vertebrates. In Drosophila melanogaster, Tehao shares a striking similarity in its intracellular domain with Toll. In this paper, we show that Tehao is expressed throughout development and appears to be glycosylated. In transiently transfected cells, Tehao activated both Dorsal and the transcription of endogenous drosomycin and metchnikowin genes. Purified recombinant Tehao interacted specifically in vitro not only with the Pelle protein kinase, but also with the Toll intracytoplasmic domain. Remarkably, Tehao was found to activate Dorsal-dependent transcription in a synergistic manner with Toll, as well as Pelle in co-transfected cells. Thus, Tehao, alone or with Toll as a multimeric complex, has the potential to participate in both the development and innate immune responses of Drosophila.

Amino Acid Sequence↗

PubMed2006

Innate immune response to human bone marrow fibroblastic cell implantation in CB17 scid/beige mice.

Immunocompromised mouse models have been extensively used to assess human cell implantation for evaluation of cytotherapy, gene therapy and tissue engineering strategies, as these mice are deficient in T and B lymphoid cells. However, the innate immune response and its effect on human cell xenotransplantation in these mouse models are mainly unknown. The aim of this study is to characterise the myeloid populations in the spleen and blood of CB17 scid beige (CB17 sb) mice, and to study the inflammatory cell responses to xenogeneic implantation of enhanced green fluorescent protein (GFP)-labelled human bone marrow fibroblastic (HBMF) cells into CB17 sb mice. The results indicate that even though CB17 sb mice are deficient in B- and T-cells, they exhibit some increases in their monocyte (Mo), macrophage (Mphi) and neutrophil (Neu) populations. NK cell and eosinophil populations show no differences compared with wild-type Balb/C mice. An innate immune response, identified by CR3 (CD11b/CD18)-positive myeloid inflammatory cells and F4/80-positive macrophages, was evident in the tissues where HBMF cells were implanted. As a consequence, the majority of implanted HBMF cells were eliminated by 4 weeks after implantation. Interestingly, the mineralised matrix formed by osteogenic HBMF cells was also eroded by multinuclear Mphi-like giant cells. We conclude that CB17 sb mice retain active innate immune cells, which respond to HBMF cell xenotransplantation. This study highlights the importance of the innate immune cells in the anti-xenograft response and suggests that strategies to block the activities of these cells may ameliorate the progressive long-term elimination of xenotransplants.

Animals↗