Introduction: Brief Overview on the Major Histocompatibility Complex
Gérard Chaouat in The Immunology of the Fetus, 2020
Two different alleles of the same histocompatibility antigen may present a different peptide derived from the same foreign antigen. The final T-cell response is, therefore, specific for both the foreign antigen and the histocompatibility antigen. This double specificity is dubbed as “MHC restriction”. The lack of reactivity to a given antigen may be due to a “hole” in the T-cell repertoire or to the lack of presentation of this antigen (or its peptides) by the histocompatibility antigens. Histocompatibility antigens are thus the filter through which the immune system recognizes the self and nonself antigens. The immunogenicity of a given antigen depends on the MHC. Some alleles are high responders, some low. This has been shown for both humoral and cellular immunity. By transfection with the corresponding MHC gene, transgenic mice have been obtained which were converted from low to high responder.
T Cells:Regulation and Cellular Immunity
Constantin A. Bona, Francisco A. Bonilla in Textbook of Immunology, 2019
Thymectomy and irradiation will eliminate all T cells, and prohibit the development of new cells, even from transplanted stem cells. A thymus graft is also necessary for reconstituting a population of mature T cells. When (α X b)F1 mice are treated in this way, and reconstituted with bone marrow cells from other (α X b)F1 mice, an α or b strain thymus graft yields T cells which recognize antigen associated with only a or b strain MHC molecules, respectively (Figure 6–10). Thus, the thymus dictates that only T cells which recognize antigens associated with MHC molecules expressed in the thymus (MHC restriction) will contribute to the repertoire. MHC restriction also determines the ability of cells to cooperate in immune responses, for example, cognate T cell help for antibody production. (MHC restriction will be discussed in greater detail in Chapter 8.) This “education” of thymocytes is not the modification of the activity or surface characteristics of individual cells. Rather, it is the selection of a group of cells which recognize non-self antigens associated with particular histocompatibility proteins, and do not respond to self epitopes. The outcome of the selection process is severe. Only 1–5% of pre-thymocytes exit the thymus as mature T cells, the remainder die.
The Defended Body
Roger Cooter, John Pickstone in Medicine in the Twentieth Century, 2020
Immunology, born from microbiology as the science of defense, thus came to resonate with the philosophical problem of the identity of the self. Molecules involved in defense reactions, such as antibodies, could serve the more general purpose of singling out the individual. If during the first decades of the century, the blood group antigens had been the main markers of this phenomenon, additional substances were described in the 1960s, this time borne by most of the cells of the organism and serving to define other human groups analogous to the blood-groups defined by red-cells. As these new molecules were involved in transplantation rejection, they were called histocompatibility leucocyte antigens (HLA system). They represented a gross mechanism for recognition of foreign cells. That human populations are, genetically, very varied in their HLA antigens has been seen as a result of evolutionary selection, perhaps permitting the human species to escape extinction when confronted with pathogens.
Comparison of the effects of colonic electrical stimulation and prucalopride on gastrointestinal transit and defecation in a canine model of constipation
Published in Scandinavian Journal of Gastroenterology, 2021
Shuo Chen, Liang Liu, Yanmei Li, Hailong Li, Xizhen Sun, Dan Zhu, Qiao Meng, Shukun Yao, Shiyu Du
Throughout the experiment, the general conditions of the animals were good, and the implanted CES system worked normally. Subcutaneous edema occurred in five dogs in the region of the embedded stimulator after surgery, but all of them recovered completely in two weeks. No other complications were found. As far as we know, a comprehensive evaluation of histocompatibility on CES system has also been carried out in this study for the first time. The evaluation of histocompatibility has been conducted both under macroscopic and microscopic observation. After the 3-month experiment duration, there was local adhesion surrounding the implanted leads. The impact of the electrodes, leads and stimulators on the colonic wall was limited to minimal inflammation and fibrosis. These histological changes are common manifestations around implanted materials. These results indicate that the CES system implantation achieved good endurance and histocompatibility with the animals. To realize the human application of this technology, a higher degree of miniaturization and biocompatibility is needed for further technical improvement.
Frequency of HLA Class I and Class II Alleles in Patients with CVID from Turkey
Published in Immunological Investigations, 2021
Begum Ozbek, Cagman Tan, Ismail Yaz, Can Kosukcu, Saliha Esenboga, Pınar Gur Cetinkaya, Deniz Cagdas, Ilhan Tezcan
The major histocompatibility complex, known as human leukocyte antigen (HLA), is a set of genes that forms a specific group of structures expressed on the cell surface and it is essential for presentation of antigens obtained from the pathogens to T cells. Also, it contributes to the development of T cells in thymus and thymic selection of the T-cell repertoire (Wieczorek et al. 2017). Detecting specific HLA allele groups has a significant role in organ and stem cell transplantation and disease associations. To date, the association between HLA alleles and various disorders. For example, 80-85% of patients with ankylosing spondylitis (AS) is HLA-B27 positive; Behçet’s disease has a high correlation with HLA-B*51, narcolepsy with HLA-DQB1*06:02 and rheumatoid arthritis (RA) with HLA-DRB1*04 (Brown 2011; Fugger and Svejgaard 2000; Miyagawa et al. 2015; Wallace 2014).
Development of local anesthetic drug delivery system by administration of organo-silica nanoformulations under ultrasound stimuli: in vitro and in vivo investigations
Published in Drug Delivery, 2021
Rong-Qin Qi, Wei Liu, Duan-Yu Wang, Fan-Qing Meng, Hong-Ying Wang, Hai-Yan Qi
To reveal the potential in vivo biocompatibility of prepared samples pain treatment, rats that got infusions of GCS-MONPs@RV with or without US irradiation were euthanized seven days and 14 days after infusion. Histomorphology of H&E recolored tissue areas showed no conspicuous harmful reaction happened amid treatment (Figure 8); however, there happened incendiary cell penetration, which is usually seen with infused samples (Gupta et al., 2017). There was no distinction in bio histocompatibility between GCS-MONPs@RV with or without US irradiation, and the kind irritation was diminished 14 days after infusion. Histocompatibility was high in every single test gathering. Hence, these outcomes showed the high histocompatibility of GCS-MONPs@RV as nano-scaffold both ex vitro and in vivo for pain relief.
Related Knowledge Centers
- Allele
- Chromosome 6
- Major Histocompatibility Complex
- Mhc Class I
- Mhc Class II
- Haplotype
- Gene
- Leukocyte Antigen
- T Cell
- Transplant Rejection
- Mhc Class II