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wow this intro is an absolute mess, in terms of style and formatting; also much too long, needs to be trimmed down to only the most critically relevant information (third and fifth paragraphs in particular) and to address with brief mentions or summaries all aspects and sub-topics related to the term "antibody" (such as their use in molecular biology research) |
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The term [[humoral immunity]] is often treated as synonymous with the antibody response, describing the function of the immune system that exists in the body's humors (fluids) in the form of soluble proteins, as distinct from [[cell-mediated immunity]], which generally describes the responses of [[T cell]]s (especially cytotoxic T cells). In general, antibodies are considered part of the [[adaptive immune system]], though this classification For example, natural IgM,<ref>{{Cite journal |last1=Ehrenstein |first1=Michael R. |last2=Notley |first2=Clare A. |date=2010-10-15 |title=The importance of natural IgM: scavenger, protector and regulator |url=http://dx.doi.org/10.1038/nri2849 |journal=Nature Reviews Immunology |volume=10 |issue=11 |pages=778–786 |doi=10.1038/nri2849 |pmid=20948548 |s2cid=35784099 |issn=1474-1733}}</ref> which are made by B-1 lineage cells that have properties more similar to innate immune cells than adaptive, refers to IgM antibodies made independently of an immune response that demonstrate polyreactivity- they recognize multiple distinct (unrelated) antigens. These can work with the [[complement system]] in the earliest phases of an immune response to help facilitate clearance of the offending antigen and delivery of the resulting [[Immune complex|immune complexes]] to the [[Lymph node|lymph nodes]] or [[spleen]] for initiation of an immune response.
In the course of an immune response, B cells can progressively [[Cellular differentiation|differentiate]] into antibody-secreting cells (B cells themselves do not secrete antibody; B cells do, however, express B cell receptors, the membrane-bound form of the antibody, on their surface) or memory B cells.<ref>{{Cite journal |last1=Akkaya |first1=Munir |last2=Kwak |first2=Kihyuck |last3=Pierce |first3=Susan K. |date=April 2020 |title=B cell memory: building two walls of protection against pathogens |journal=Nature Reviews Immunology |language=en |volume=20 |issue=4 |pages=229–238 |doi=10.1038/s41577-019-0244-2 |pmid=31836872 |pmc=7223087 |issn=1474-1741}}</ref> Antibody-secreting cells comprise plasmablasts and [[Plasma cell|plasma cells]], which differ mainly in the degree to which they secrete antibody, their lifespan, metabolic adaptations, and surface markers.<ref>{{Cite journal |last1=Tellier |first1=Julie |last2=Nutt |first2=Stephen L |date=2018-10-15 |title=Plasma cells: The programming of an antibody-secreting machine |url=http://dx.doi.org/10.1002/eji.201847517 |journal=European Journal of Immunology |volume=49 |issue=1 |pages=30–37 |doi=10.1002/eji.201847517 |pmid=30273443 |issn=0014-2980|hdl=11343/284565 |hdl-access=free }}</ref> Plasmablasts are rapidly proliferating, short-lived cells produced in the early phases of the immune response (classically described as arising extrafollicularly rather than from the [[germinal center]]) which have the potential to differentiate further into plasma cells.<ref>{{Citation |title=B Cell Memory and Plasma Cell Development |date=2015 |work=Molecular Biology of B Cells |pages=227–249 |url=https://linkinghub.elsevier.com/retrieve/pii/B978012397933900014X |access-date=2024-01-24 |publisher=Elsevier |language=en |doi=10.1016/b978-0-12-397933-9.00014-x |isbn=978-0-12-397933-9}}</ref>
Antibodies are central to the immune protection elicited by most vaccines and infections (although other components of the immune system certainly participate and for some diseases are considerably more important than antibodies in generating an immune response, e.g. [[Shingles|herpes zoster]]).<ref>{{Cite journal |last=Plotkin |first=Stanley A. |date=2022 |title=Recent updates on correlates of vaccine-induced protection |journal=Frontiers in Immunology |volume=13 |pages=1081107 |doi=10.3389/fimmu.2022.1081107 |doi-access=free |issn=1664-3224 |pmc=9912984 |pmid=36776392}}</ref> Durable protection from infections caused by a given microbe – that is, the ability of the microbe to enter the body and begin to replicate (not necessarily to cause disease) – depends on sustained production of large quantities of antibodies, meaning that effective vaccines ideally elicit persistent high levels of antibody, which relies on long-lived plasma cells. At the same time, many microbes of medical importance have the ability to mutate to escape antibodies elicited by prior infections, and long-lived plasma cells cannot undergo affinity maturation or class switching. This is compensated for through memory B cells: novel variants of a microbe that still retain structural features of previously encountered antigens can elicit memory B cell responses that adapt to those changes. It has been suggested that long-lived plasma cells secrete B cell receptors with higher affinity than those on the surfaces of memory B cells, but findings are not entirely consistent on this point.<ref>{{Cite journal |last1=Sutton |first1=Henry J. |last2=Gao |first2=Xin |last3=Kelly |first3=Hannah G. |last4=Parker |first4=Brian J. |last5=Lofgren |first5=Mariah |last6=Dacon |first6=Cherrelle |last7=Chatterjee |first7=Deepyan |last8=Seder |first8=Robert A. |last9=Tan |first9=Joshua |last10=Idris |first10=Azza H. |last11=Neeman |first11=Teresa |last12=Cockburn |first12=Ian A. |date=2024-01-12 |title=Lack of affinity signature for germinal center cells that have initiated plasma cell differentiation |url=https://pubmed.ncbi.nlm.nih.gov/38228150 |journal=Immunity |pages=S1074–7613(23)00541–1 |doi=10.1016/j.immuni.2023.12.010 |issn=1097-4180 |pmid=38228150}}</ref>
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