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Comparative Immunology
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
Hagfish kept under good conditions in a warm environment can reject skin allografts. First-set grafts take about seventy-two days at 18°C to be rejected; second-set grafts are rejected in about twenty-eight days. This suggests that immunologic memory has developed. Lampreys also reject skin allografts slowly, and their lymphocytes will divide in the presence of cells from a second lamprey and phytohemagglutinin. Elasmobranchs reject scale allografts slowly as do lampreys but bony fish reject them rapidly. Repeated grafting leads to accelerated graft rejection. The rejected allografts are infiltrated by lymphocytes and show destruction of blood vessels and pigment cells. As in all ectotherms, graft rejection is slower at lower temperatures.
Basics of Allergy
Published in Pudupakkam K Vedanthan, Harold S Nelson, Shripad N Agashe, PA Mahesh, Rohit Katial, Textbook of Allergy for the Clinician, 2021
Rafeul Alam, Dipa K Sheth, Magdalena M Gorska
The immune system is composed of an adaptive immune system and an innate immune system. The adaptive immune system distinguishes itself from the innate system by the following features: (a) Specificity of antigen recognition, (b) Diversity of the antigen receptor repertoire, (c) Rapid clonal expansion, (d) Adaptiveness to the changing environment and (e) Immunological memory. The innate system lacks fine specificity, has limited diversity and rudimentary memory but manifests rapid engagement. Lymphocytes are the primary cells of adaptive immunity; they include T cells, B cells and NK cells. Each individual cell type will be described in this chapter.
Summary, Conclusions, and Implications
Published in T. D. Luckey, Radiation Hormesis, 2020
Immune competence was increased by exposures to ionizing radiation. Increased DNA repair capabilities occured in lightly exposed humans and animals; these and other cellular repair systems occur in most active cells. Some cells retained immunologic memory for decades. For example, Japanese survivors of atom bombs showed increased lymphocytic mitogen stimulation after 40 years. The biopositive effects of low doses of ionizing radiation in immunity include increased numbers of circulating lymphocytes, faster wound healing following skin incision, increased resistance to lethal doses of ionizing radiation, and decreased infection and cancer morbidity and mortality. The cumulative effect of increased immune competence was to increase the quality of life and the average lifespan. Increased immune competence and cellular repair systems provided partial explanations for the reduced cancer incidence and mortality found following low doses of ionizing radiation.
The prevalence of adaptive immunity to COVID-19 and reinfection after recovery – a comprehensive systematic review and meta-analysis
Published in Pathogens and Global Health, 2022
Tawanda Chivese, Joshua T. Matizanadzo, Omran A. H. Musa, George Hindy, Luis Furuya-Kanamori, Nazmul Islam, Rafal Al-Shebly, Rana Shalaby, Mohammad Habibullah, Talal A. Al-Marwani, Rizeq F. Hourani, Ahmed D. Nawaz, Mohammad Z. Haider, Mohamed M. Emara, Farhan Cyprian, Suhail A. R. Doi
This synthesis suggests, for a period of at least 6–8 months after recovery, around 90% of individuals have evidence of SARS-CoV-2 specific memory B and memory CD4+ cells while about half have evidence of CD8+ cells. While the role of T cells in sterilizing immunity is thought to be limited, they are highly associated with ensuring less severe COVID-19 [73,111]. A diminished prevalence of cytotoxic CD8+ cells may imply that viral clearance is delayed in some individuals, in the event of reinfection. However, there is evidence of sustained high prevalence of T follicular helper cells (TFH) [9], a subset of CD4 + T cells that are the most important in helping memory B cells and in the production of neutralizing antibodies and long-term humoral immunity [99]. A high prevalence of memory B cells at ≥6 months also suggests that immunological memory may be long lasting, at least to the time points measured in the included studies.
Immunologic underpinnings and treatment of morphea
Published in Expert Review of Clinical Immunology, 2022
Avery H. LaChance, Nathaniel Goldman, Bina Kassamali, Ruth Ann Vleugels
The adaptive immune system produces a specific, targeted, and coordinated immune response following initial innate immune reactions. Adaptive immunity is responsible for the production of immunologic memory through the coordinated actions of T cells and B cells. Within the adaptive immune system, a more recent hypothesis has suggested that tissue fibrosis results from an imbalance in the Th1/Th2 pathways, with a general shift in the Th2 direction [36,37]. However, other studies support a predominant role of cytokines in the Th1 and Th17 pathways in the development of morphea [38]. Ultimately, the exact pathophysiologic march leading to morphea is not yet clear, but more recent studies have suggested a role for cytokines from all three pathways to potentially play a causative role in the development of morphea, including early inflammation triggered by a Th1/Th17 response and subsequent fibrosis driven by the Th2 pathway later in the course of disease [39]. Given that cytokines from each of these pathways are elevated at differing stages of disease development, this more recent hypothesis is gaining in popularity.
The current and future role of nanovaccines in HIV-1 vaccine development
Published in Expert Review of Vaccines, 2021
Christopher P. Karch, Gary R. Matyas
HIV-1 has remained a global pandemic since the 1980s. Despite the successes that have occurred with anti-retroviral therapies, it is unlikely that the virus will be eliminated from the population without an efficacious vaccine [1]. The vaccine development process has been ongoing for almost as long as the pandemic has existed; however, the basic biology of the virus has consistently hampered vaccine development [2]. At the most basic level, HIV-1 is a highly diverse retrovirus that has an error prone reverse transcriptase, which leads to high levels of viral diversity [3]. In addition, HIV-1 DNA can be integrated into the genome of infected cells. Furthermore, there is not a complete understanding of the immune responses necessary to prevent an infection [1]. Moreover, HIV-1 infects CD4+ cells, key components of the immune system, further hampering the immune response [4,5]. Classically, vaccines induce immunological memory, which becomes activated during the early stages of infection and results in a rapid clearing of the infection. The high viral diversity and the ability to of the HIV-1 DNA to be integrated into the genome make a broadly efficacious vaccine a difficult target to obtain.