The Invisible Army
Norman Begg in The Remarkable Story of Vaccines, 2023
If the invader makes it past the first lines of defence, they encounter a much craftier response team. Your white blood cells (called leucocytes) are a highly disciplined and adaptable workforce. Leucocytes have evolved into different types, each with a specific function. Some swallow and destroy invaders without further ado, others instruct your body to produce antibodies. The job of this workforce is to give you immunity – your ability to protect yourself from infectious diseases. There are two arms of the immune system; antibodies and cells. Antibodies are produced by a specialised type of white blood cell known as a lymphocyte, specifically a B lymphocyte (or B cell). Antibodies have an arsenal of weapons which they use to deal with invaders. They can neutralise them with toxins, block them from getting into cells, and prevent them from multiplying. The cells involved in immunity are called T lymphocytes (T cells). They order the B cells to make antibodies and control the overall immune response. They also destroy cells that have been infected. The names T cell and B cell derive from where they were first discovered: T cells from the thymus gland (which sits behind your breastbone) and B cells from the Bursa of Fabricius, an organ found only in birds.
Dopamine in the Immune and Hematopoietic Systems
Nira Ben-Jonathan in Dopamine, 2020
B lymphocytes also develop from hematopoietic progenitors in the bone marrow, where they undergo the initial process of differentiation and selection [6]. They are distinguished from T cells and NK cells by the expression of the B cell receptor (BCR) on their plasma membrane. Development of B cells occurs in several stages, marked by various patterns of gene expression, and an arrangement of the immunoglobulin H chain and L chain gene loci. They also undergo the V(D)J recombination of their immunoglobulins. To complete their development, immature B cells migrate from the bone marrow to the spleen. Once fully differentiated, B cells can secrete antibodies and comprise the humoral component of the adaptive immunity. In addition, B cells present antigen and secrete cytokines. The BCR enables each B cell clone to bind a specific antigen and initiate an antibody response. Activation of B cells occurs via antigen recognition by BCRs and requires a secondary activation signal provided either by T helper cells or by the antigen itself.
Autoimmune disorders
Judy Bothamley, Maureen Boyle in Medical Conditions Affecting Pregnancy and Childbirth, 2020
The immune system is a complex network of specialised cells, tissues, organs and chemical signals interacting together to provide a defence against pathogens. There are two aspects to the system: innate immunity (or in-built immunity), which is present all the time and acts as a first line of defence (see Box 12.1) and adaptive immunity. Adaptive immunity (specific or acquired immunity) responds specifically to particular antigens (an antigen is any substance perceived by the body as foreign). Adaptive immunity is the type of immunity that, rather than being fully present at birth, develops throughout life. The foreign pathogens are attacked by T lymphocytes. B lymphocytes and other specialised immune system cells act with T lymphocytes to produce antibodies that attach directly to the antigen. Antibodies also stimulate the release of special chemical mediators in blood (e.g., complement or interferon) that further aid antigen destruction.
Immunology of HPV-mediated cervical cancer: current understanding
Published in International Reviews of Immunology, 2021
Babban Jee, Renu Yadav, Sangeeta Pankaj, Shivendra Kumar Shahi
B lymphocytes are universally known for their ability to produce antibodies in addition to presenting antigen to T cells and secreting cytokines. These cells can develop immunoregulatory properties during infection [155] and autoimmune disorders [156]. Available evidences indicate that B cells may also play immunoregulatory role in cancer [157]. However, precise role of B cells in tumor immunity, particularly in HPV-mediated cervical cancer, remains unclear. Using a TC-1 mouse model of HPV-induced cervical cancer, Tang et al. have demonstrated that B cells promote tumor progression and contribute in establishing the tumor favoring microenvironment [158]. This study also suggests that targeting of B cells may be beneficial in improving vaccines efficacy in patients. In contrast, Kim and coworkers recently found that B cells promote overall survival of patients suffering with HPV -associated cancers including cervical cancer and activated with the radiotherapy and PD-1 blockade [159]. Further, in a another patients based study, it was shown that B reg cells, a subset of B cells, are elevated in HPV related cervical cancer and have strong association with tumor progression and metastasis. B cells have also found to impair function of CD8+ T cells [160].
COVID-19: captures iron and generates reactive oxygen species to damage the human immune system
Published in Autoimmunity, 2021
B lymphocytes differentiates into long-lived antibody-forming cells and memory B cells that produce antibodies [83]. Differentiation process of B cells is divided into five stages: pre-B cells, immature B cells, mature B cells, activated B cells and plasma cells. The differentiation of pre-B cells and immature B cells is an antigen-independent process that takes place in the bone marrow. Meanwhile, during the antigen-dependent stage, mature B cells are stimulated by antigens and continuously differentiate into plasma cells that synthesise and secrete antibodies. The differentiation at this stage is mainly carried out in the peripheral immune organs. The differentiation of most memory B cells depends on the germinal centres of lymph nodes. Abnormal regulation of spontaneous centres (Spt-GCs) is thought to promote mutations of antibody secreting cells and autoimmune diseases [84]. Although it has been reported that the SARS-COV-2 virus has been found in lymph nodes, the existing evidence still does not strongly support the virus infecting lymphocytes, especially B cells.
The Potential Role of PTPN-22 C1858T Gene Polymorphism in the Pathogenesis of Type 1 Diabetes in Saudi Population
Published in Immunological Investigations, 2018
Khaled A. Alswat, Amre Nasr, Mohammed S. Al Dubayee, Iman M. Talaat, Adnan A. Alsulaimani, Imad A.A. Mohamed, Gamal Allam
PTPN-22 is the most influential gene outside HLA loci associated with T1D susceptibility (Stanford and Bottini, 2014). A single nucleotide polymorphism (SNP) at position 1858 (rs 2476601, also known as R620W or C1858T) of the encoding sequence of PTPN-22 gene, consisting of the substitution of cytosine by thymine, results in mutation of arginine (R) to tryptophan (W) at codon 620 (R620W) of LYP. As LYP is expressed in many cell types of both innate and adaptive immunities, such mutation could affect the autoimmunity via the regulation of immune cells activation (Begovich et al., 2004). Specifically, this mutation disturbs the LYP–CSK interaction and causes alterations in BCR signal transduction as well as increased resistance to apoptosis (Habib et al., 2012; Rieck et al., 2007). Consequently, this will lead to increased survival of transitional and naive B lymphocytes (Gianchecchi et al., 2013). Indeed, asymptomatic individuals carrying the PTPN-22 1858T allele showed high frequencies of auto-reactive B lymphocytes in their blood comparable to patients with T1D, rheumatoid arthritis (RA), and systemic lupus erythematosus (SLE) (Menard et al., 2011). In addition, the PTPN-22 1858T allele has been suggested to alter LYP function in Treg cells and may render it less effective in damping autoimmune response, leading to destruction of insulin-producing β cell and consequently a major loss in β-cell function in individuals carrying this allele (Bottini et al., 2006).
Related Knowledge Centers
- Adaptive Immune System
- Antibody
- Antigen Presentation
- Humoral Immunity
- Memory B Cell
- White Blood Cell
- Lymphocyte
- Cytokine
- B-Cell Receptor
- Antigen-Presenting Cell