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Basic Chemical Hazards to Human Health and Safety — II
Published in Jack Daugherty, Assessment of Chemical Exposures, 2020
Lymphocytes that produce humoral immunity are called B-cells. Antibodies (Ab) and immunoglobulins (Ig) are proteins on the surface of B-cells. The most abundant immunoglobulin, IgG, from about seven weeks of age onward, produces a secondary response to antigens. Before that age, the infant relies on IgG transferred from its mother transplacentally. IgM primary response antibodies active the complement pathway early in the immune response. IgA is the primary immunoglobulin found in body secretions, such as saliva, tears, and colostrum, and which are the first line of defense in respiratory and gastrointestinal infections. IgD is an important part of B-cell differentiation. IgE attaches to mast cells and other leukocytes.
Human physiology, hazards and health risks
Published in Stephen Battersby, Clay's Handbook of Environmental Health, 2023
Revati Phalkey, Naima Bradley, Alec Dobney, Virginia Murray, John O’Hagan, Mutahir Ahmad, Darren Addison, Tracy Gooding, Timothy W Gant, Emma L Marczylo, Caryn L Cox
There are five classes of antibodies: Immunoglobulin A (IgA) is found in secretions such as saliva, tears and protects against organisms that may invade gastrointestinal and respiratory tracts.Immunoglobulin M (IgM) which is formed initially and provides a temporary protection following exposure of the body to a new threat until immunoglobulin G is made.Immunoglobulin G (IgG) takes over from IgM to provide long-lasting protection against a specific threat.Immunoglobulin E (IgE) (sometimes called the ‘allergy’ antibody) is responsible for allergic reactions. IgE is usually produced against harmful substances but in some cases with an inherited disorder, IgE is formed in excessive amounts to substances that are usually not harmful to the majority of the population. These ‘atopic’ individuals thus react abnormally or disproportionately to a substance that should be harmless.Immunoglobulin D (IgD) is a unique immunoglobulin with a concentration in serum far below those of IgG, IgA and IgM but much higher than that of IgE. IgD’s function has long been a conundrum and is still incompletely understood. Several chemicals are produced by the body in allergic responses, of which histamine is the best known and causes the well-known symptoms of itching, swelling, redness and increased production of mucus.
Autologous Hematopoietic Stem Cell Transplantation for Crohn’s Disease
Published in Richard K. Burt, Alberto M. Marmont, Stem Cell Therapy for Autoimmune Disease, 2019
Robert M. Craig, Richard K. Burt
LPL are located between the epithelial basement membrane and muscularis mucosa.2 In contrast to IEL, most LPL are CD4+ with a CD4/CD8 ratio of approximately 2:1. LPL may express either the γ/δ TCR or more commonly α/β TCR. While LPL function remains poorly understood, most are considered to be helper memory α/β T lymphocytes involved in B cell secretory IgA production. IgA is the predominate immunoglobulin produced by gut B cells and is secreted into the lumen. Intraluminal IgA agglutinates infectious agents preventing their adherence to and penetration through enterocytes.
The perinatal period, the developing intestinal microbiome and inflammatory bowel diseases: What links early life events with later life disease?
Published in Journal of the Royal Society of New Zealand, 2020
Fathalla Ali, Kei Lui, Alex Wang, Andrew S. Day, Steven T. Leach
IgA is the most abundant immunoglobulin secreted by B cells across the mucus membrane (Macpherson et al. 2012). Most of the IgA producing B cells mature in the gastrointestinal tract upon stimulation by commensal bacteria (Kamada and Nunez 2014). Even though microbiota is crucial for the differentiation of intestinal B cells, different types of bacteria have a different influence on B cell development and IgA production. For example in a germ-free mouse model, intestinal colonisation with SFB resulted in more IgA producing B-cells compared to intestinal colonisation with Clostridia (Umesaki et al. 1999). Furthermore, colonisation with any bacteria results in more IgA producing B-cell compared to no intestinal bacteria (Umesaki et al. 1999).