Realization of a self-recognition algorithm based on the biological immune system

As the use of the computer is popularized, the damage from computer viruses and hacking by malicious users is increasing rapidly. To block the hacking that is an intrusion into a person's computer, and the viruses that destroy data, a study into an intrusion detection and virus detection system based on the biological immune system is in progress. In this article, we describe a model of positive and negative selection for self-recognition, which has a similar function to the cytotoxic T cells that play an important role in the biological immune system. We propose a self/nonself discrimination algorithm for a computer system, which will the important when we detect data infected by a computer virus, of data modified by an intrusion from outside. We also show the validity and effectiveness of the proposed self-recognition algorithm by a computer simulation of some infected data obtained from cell changes and string changes in the self-file. This work was presented, in part, at the Seventh International Symposium on Artificial Life and Robotics, Oita, Japan, January 16–18, 2002     

COVID-19 Pandemic: Escape of Pathogenic Variants and MHC Evolution

We propose a new hypothesis that explains the maintenance and evolution of MHC polymorphism. It is based on two phenomena: the constitution of the repertoire of naive T lymphocytes and the evolution of the pathogen and its impact on the immune memory of T lymphocytes. Concerning the latter, pathogen evolution will have a different impact on reinfection depending on the MHC allomorph. If a mutation occurs in a given region, in the case of MHC allotypes, which do not recognize the peptide in this region, the mutation will have no impact on the memory repertoire. In the case where the MHC allomorph binds to the ancestral peptides and not to the mutated peptide, that individual will have a higher chance of being reinfected. This difference in fitness will lead to a variation of the allele frequency in the next generation. Data from the SARS-CoV-2 pandemic already support a significant part of this hypothesis and following up on these data may enable it to be confirmed. This hypothesis could explain why some individuals after vaccination respond less well than others to variants and leads to predict the probability of reinfection after a first infection depending upon the variant and the HLA allomorph.     

Embedding in Spurr's resin is a good choice for immunolabelling after freeze drying as shown with chemically unfixed dendritic cells

Immunocytochemical reactions on biological specimens depend on many factors, the most crucial one being the maintenance of antigenicity. Antigens are vulnerable at each stage during preparation for electron microscopy. One of the least traumatic methods of preparing biological tissues for post‐embedding immunolabelling includes the following steps: (1) physical stabilization of the native biological material by rapid freezing (cryofixation) and keeping the immobilized biological sample at low temperature, thereby avoiding any movements of water, ions and macromolecules; (2) dehydrating the frozen biological material by freeze‐drying at low temperature; (3) embedding of the dehydrated specimen. Here we show that embedding of chemically unfixed dendritic cells in Spurr's resin after cryofixation and freeze‐drying enables the conservation of fine ultrastructure without cell distortion or shrinkage. Furthermore, we demonstrate the feasibility of protein localization in ultrathin sections by immunolabelling of the major histocompatibility class II molecules.     

纳秒脉冲触发的阵列微空心阴极放电特性

阵列微空心阴极(MHC)是一种在同一个阴极结构上加工多个微孔形成微孔阵列,实现大面积高电子密度的放电微等离子体结构。相比直流触发模式,纳秒短脉冲触发阵列微空心阴极,可以显著地减少直流触发时的电流热负荷效应,提高放电电流和放电能量。本文利用自行研制的纳秒脉冲电源,实现对阵列微空心阴极在氩气下进行脉冲放电,研究其脉冲条件下的放电特性;其次,研究其在纳秒脉冲下多孔阵列的同步放电问题,并通过加入预触发结构,有效改善其同步特性;最后,利用光纤式发射光谱仪进行氩气下氩发射光谱测量,并对纳秒放电等离子体进行光谱诊断。     

MHC合金粉末冶金制备及其锻造棒材力学性能研究

针对MHC合金粉末的冶金制备工艺及其烧结坯性能、锻造态和经热处理后的MHC合金棒组织与力学性能开展研究。结果表明:所研究的粉末冶金工艺参数可制备出适宜于锻造加工的MHC烧结棒坯;相比于烧结坯,经88.6%锻造比锻造后MHC合金棒材的硬度、强度显著提高;经88.6%锻造比锻造后的MHC合金棒材的完全再结晶温度高于1500℃,经1200℃保温1 h热处理后,MHC合金棒材的室温强度Rp 0.2>770 MPa,硬度达到HRA 66.5;真空气氛下800℃高温拉伸强度Rp 0.2>450 MPa,延伸率大于18.5%。表明本研究制备的MHC合金棒材具备显著的室温高强高硬特性和良好的高温综合力学性能。     

TCR Recognition of Peptide–MHC-I: Rule Makers and Breakers

T cells are a critical part of the adaptive immune system that are able to distinguish between healthy and unhealthy cells. Upon recognition of protein fragments (peptides), activated T cells will contribute to the immune response and help clear infection. The major histocompatibility complex (MHC) molecules, or human leukocyte antigens (HLA) in humans, bind these peptides to present them to T cells that recognise them with their surface T cell receptors (TCR). This recognition event is the first step that leads to T cell activation, and in turn can dictate disease outcomes. The visualisation of TCR interaction with pMHC using structural biology has been crucial in understanding this key event, unravelling the parameters that drive this interaction and their impact on the immune response. The last five years has been the most productive within the field, wherein half of current unique TCR–pMHC-I structures to date were determined within this time. Here, we review the new insights learned from these recent TCR–pMHC-I structures and their impact on T cell activation.     

The HLA-G Immune Checkpoint Plays a Pivotal Role in the Regulation of Immune Response in Autoimmune Diseases

The human G-leukocyte antigen (HLA-G) molecule is a non-classical major histocompatibility complex (MHC) class I molecule. The pertinence of HLA-G has been investigated in numerous studies which have sought to elucidate the relevance of HLA-G in pathologic conditions, such as autoimmune diseases, cancers, and hematologic malignancies. One of the main goals of the current research on HLA-G is to use this molecule in clinical practice, either in diagnostics or as a therapeutic target. Since HLA-G antigens are currently considered as immunomodulatory molecules that are involved in reducing inflammatory and immune responses, in this review, we decided to focus on this group of antigens as potential determinants of progression in autoimmune diseases. This article highlights what we consider as recent pivotal findings on the immunomodulatory function of HLA-G, not only to establish the role of HLA-G in the human body, but also to explain how these proteins mediate the immune response.