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The Invisible Army
Published in Norman Begg, The Remarkable Story of Vaccines, 2023
Vaccines work on the immune system in much the same way as invading bacteria and viruses. The immune system recognises a specific component in the vaccine, the antigen, and gets to work. Both T cells and B cells are involved in the response to a vaccine. Vaccines trigger an immune response, but not immediately. It takes time for the antigen to be recognised and processed by the immune system. Detectable antibodies usually start to appear seven to ten days after a vaccine is given. Sometimes the first attempt at antibody production is rather feeble, so you need to give a second or third vaccination. However, once you have decent antibody levels, you are in good shape. Your immune system has a spectacular memory. Some of your B cells – memory cells – are dedicated to committing information to a long-term memory bank. When it encounters the virus or bacterium, even after many years, the task force is quickly reassembled and swings into action immediately. There are also times when you need to jog the memory, by a booster vaccination; vaccine-induced immunological memory can be with you for life. It’s more than thirty years since I was vaccinated against hepatitis A, and I am still protected. A certificate of vaccination against yellow fever is valid for life, thanks to immunological memory.
Immunology of T Cells in AIDS: Dynamics Revealed by Eight-Color Flow Cytometry
Published in Thomas F. Kresina, Immune Modulating Agents, 2020
Mario Roederer, Stephen C. De Rosa, Leonore A. Herzenberg, Leonard A. Herzenberg
The loss of naive CD8 T cells predicates that the memory CD8 compartment is expanding—since total CD8 counts are elevated and remain relatively stable during most of the disease. It was found over a decade ago that there is a significant increase in CD8 T cells bearing an activation phenotype (CD38+ HLA-DR+) [4]. Presumably, these cells are involved in immune responses in the individual (against HIV or other pathogens). What about the remaining CD8 T cells, those not involved in responses to HIV and concurrent pathogens? These cells, after all, underlie the basic immunological memory that protects against future pathogenic infections.
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.
Inhaled vaccine delivery in the combat against respiratory viruses: a 2021 overview of recent developments and implications for COVID-19
Published in Expert Review of Vaccines, 2022
Rick Heida, Wouter LJ Hinrichs, Henderik W Frijlink
Although pulmonary vaccination holds promise as an alternative to parenteral vaccination, there are also some critical factors that should be addressed. While the mucosal immune system likely plays a key role in defending the respiratory tract from pathogenic invasion, exuberant immune responses may deteriorate the lungs and counter-intuitively result in (antibody-dependent) enhancement of respiratory disease. The idea of an overreacting immune system in COVID-19 patients, for example, has been confirmed by studies showing that severe cases correlate with higher IgA titers [101–103] and are in some cases associated with excessive immune reactions leading to cytokine storms [36,37,104]. Therefore, the potential role of IgA in adverse events such as antibody-dependent cellular cytotoxicity or antibody-dependent enhancement should be carefully monitored during the evaluation of inhaled vaccines. Some studies have implicated that the presence of iBALT may lead to exacerbated immune responses in individuals infected with respiratory syncytial virus [30]. This might indicate that the presence of immunological memory can induce an over-reacting immune response upon vaccination. Notwithstanding this, a recent systematic review by Serazin et al., who investigated the incidence of acute respiratory distress syndrome (ARDS) after vaccination, revealed that no cases of ARDS after vaccination have been reported for any of the currently licensed vaccines [105]. Together with the lack of profound adverse events in studies about inhaled vaccination, we believe that the risks for such severe adverse events is minimal.
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.