Development of a human adaptive immune system in cord blood cell-transplanted mice

Because ethical restrictions limit in vivo studies of the human hemato-lymphoid system, substitute human to small animal xenotransplantation models have been employed. Existing models, however, sustain only limited development and maintenance of human lymphoid cells and rarely produce immune responses. Here we show that intrahepatic injection of CD34+ human cord blood cells into conditioned newborn Rag2-/-gammac-/- mice leads to de novo development of B, T, and dendritic cells; formation of structured primary and secondary lymphoid organs; and production of functional immune responses. This provides a valuable model to study development and function of the human adaptive immune system in vivo.     

Asymmetric T lymphocyte division in the initiation of adaptive immune responses

A hallmark of mammalian immunity is the heterogeneity of cell fate that exists among pathogen-experienced lymphocytes. We show that a dividing T lymphocyte initially responding to a microbe exhibits unequal partitioning of proteins that mediate signaling, cell fate specification, and asymmetric cell division. Asymmetric segregation of determinants appears to be coordinated by prolonged interaction between the T cell and its antigen-presenting cell before division. Additionally, the first two daughter T cells displayed phenotypic and functional indicators of being differentially fated toward effector and memory lineages. These results suggest a mechanism by which a single lymphocyte can apportion diverse cell fates necessary for adaptive immunity.     

Glycosylation and the immune system

Almost all of the key molecules involved in the innate and adaptive immune response are glycoproteins. In the cellular immune system, specific glycoforms are involved in the folding, quality control, and assembly of peptide-loaded major histocompatibility complex (MHC) antigens and the T cell receptor complex. Although some glycopeptide antigens are presented by the MHC, the generation of peptide antigens from glycoproteins may require enzymatic removal of sugars before the protein can be cleaved. Oligosaccharides attached to glycoproteins in the junction between T cells and antigen-presenting cells help to orient binding faces, provide protease protection, and restrict nonspecific lateral protein-protein interactions. In the humoral immune system, all of the immunoglobulins and most of the complement components are glycosylated. Although a major function for sugars is to contribute to the stability of the proteins to which they are attached, specific glycoforms are involved in recognition events. For example, in rheumatoid arthritis, an autoimmune disease, agalactosylated glycoforms of aggregated immunoglobulin G may induce association with the mannose-binding lectin and contribute to the pathology.     

Diversity and function of adaptive immune receptors in a jawless vertebrate

Instead of the immunoglobulin-type antigen receptors of jawed vertebrates, jawless fish have variable lymphocyte receptors (VLRs), which consist of leucine-rich repeat (LRR) modules. Somatic diversification of the VLR gene is shown here to occur through a multistep assembly of LRR modules randomly selected from a large bank of flanking cassettes. The predicted concave surface of the VLR is lined with hypervariable positively selected residues, and computational analysis suggests a repertoire of about 10(14) unique receptors. Lamprey immunized with anthrax spores responded with the production of soluble antigen-specific VLRs. These findings reveal that two strikingly different modes of antigen recognition through rearranged lymphocyte receptors have evolved in the jawless and jawed vertebrates.     

Promiscuity and the primate immune system

The behavioral and ecological factors involved in immune system evolution remain poorly explored. We present a phylogenetic analysis of white blood cell counts in primates to test three hypotheses related to disease risk: increases in risk are expected with group size or population density, exposure to soil-borne pathogens, and mating promiscuity. White blood cell counts were significantly greater in species where females have more mating partners, indicating that the risk of sexually transmitted disease is likely to be a major factor leading to systematic differences in the primate immune system.     

虾类免疫系统组成及免疫机理探讨

研究对虾免疫系统和免疫机理,有效提高对虾自身抗病力,被认为是解决虾病暴发的根本途径之一。本文就虾类免疫系统及免疫机理研究作一综述,以期为开展虾类免疫防病工作提供理论基础。从免疫进化角度,虾类的免疫系统仅由遗传控制的组织相容性反应和中胚层起源的效应细胞组成,不具     

虾类免疫系统组成及免疫机理探讨

研究对虾免疫系统和免疫机理,有效提高对虾自身抗病力,被认为是解决虾病暴发的根本途径之一。本文就虾类免疫系统及免疫机理研究作一综述,以期为开展虾类免疫防病工作提供理论基础。从免疫进化角度,虾类的免疫系统仅由遗传控制的组织相容性反应和中胚层起源的效应细胞组成,不具     

集体林权制度改革中主要利益相关者的选择研究

[目的]在集体林权制度改革的众多利益主体中确定主要利益相关者,为深入剖析改革中的利益配比关系和研究此类相关问题提供参考借鉴.[方法]采用美国著名学者米切尔的三要素评分法,从合法性、权力性、紧急性3个属性入手对集体林权制度改革中主要利益相关者进行探讨分析.[结果]集体林权制度改革中的主要利益相关者为集体林的经营者、政策的制定者、普通农户及村集体,在主要利益相关者之间,不同利益需求使他们各自在参与集体林权制度改革的过程中表现出显著的利益竞争或冲突,同时又有利益需求的一致性.[结论]主要利益相关者对集体林权制度改革的发展进程产生重要影响,他们之间的利益冲突会因改革的推进而不断变化,同时利益需求也会随之产生波动,促使三者间的利益需求达到均衡才是集体林权制度改革成功的关键所在.     

A neuroendocrine marker in tissues of the immune system

Antibodies to chromogranin, a secretory protein marker for the diffuse neuroendocrine system, were used to analyze rat lymphoreticular tissues by means of immunochemistry and immunohistochemistry. Chromogranin-positive cells were present in spleen, lymph node, thymus, and fetal liver. When these organs were gently dispersed and separated on a Ficoll gradient, the chromogranin-immunoreactive cells became enriched in the dense red-cell pellets. The unexpected distribution of these neuroendocrine cells in all immunologically relevant structures suggests that they may link the nervous and immunological systems.     

RNA silencing: the genome's immune system

Genomes are databases sensitive to invasion by viruses. In recent years, a defense mechanism has been discovered, which turns out to be conserved among eukaryotes. The system can be compared to the immune system in several ways: It has specificity against foreign elements and the ability to amplify and raise a massive response against an invading nucleic acid. The latter property is beginning to be understood at the molecular level.     

Interactions between the microbiota and the immune system

The large numbers of microorganisms that inhabit mammalian body surfaces have a highly coevolved relationship with the immune system. Although many of these microbes carry out functions that are critical for host physiology, they nevertheless pose the threat of breach with ensuing pathologies. The mammalian immune system plays an essential role in maintaining homeostasis with resident microbial communities, thus ensuring that the mutualistic nature of the host-microbial relationship is maintained. At the same time, resident bacteria profoundly shape mammalian immunity. Here, we review advances in our understanding of the interactions between resident microbes and the immune system and the implications of these findings for human health.     

仔猪感染PCV2后空肠黏膜免疫系统中相关免疫细胞变化

[目的]分析PCV2感染后对仔猪空肠免疫功能的影响.[方法]将6头断奶仔猪随机分为PCV2感染组和空白组,通过流式细胞术分析仔猪空肠中诱导部位和效应部位相关免疫细胞变化.[结果]结果显示,与空白组相比,PCV2感染组诱导部位PP结中总T淋巴细胞、活化/记忆T细胞和细胞毒性T细胞百分率极显著增高(P＜0.01),B细胞百分率显著增加(P＜0.05);效应部位固有层中树突状细胞(DCs)、B细胞、活化/记忆T细胞和细胞毒性T细胞百分率极显著增高(P＜0.01),DCs表面抗原递呈相关分子CD80/86与MHCⅡ表达量、总T淋巴细胞、NK细胞百分率显著上调(P＜0.05),而黏膜层中总T淋巴细胞、活化/记忆T细胞和细胞毒性T细胞、NK细胞百分率极显著增高(P＜0.01).[结论]结果表明PCV2感染导致空肠黏膜免疫系统中树突状细胞及各类淋巴细胞数量的增加,可能影响了空肠黏膜的免疫功能,提示其与PCV2临床感染引起肠炎的发生存在一定相关性.     

Study of the adaptive potential of new immune and highly scab-resistant apple tree forms

Laboratory and field data from a study of apple tree forms with different chromosome numbers used in breeding for scab resistance and unfavorable environmental factors are given.