Χρήστης:Dmtrs32/πρόχειρο: Διαφορά μεταξύ των αναθεωρήσεων

B cells develop from [[Hematopoietic stem cell|hematopoietic stem cells (HSCs)]] that originate from [[bone marrow]].<ref name="BCDTfBcells">{{cite journal | vauthors = Fischer U, Yang J, Sanchez-Garcia I | title = Cell Fate Decisions: The Role of Transcription Factors in Early B-cell Development and Leukemia | journal = Blood Cancer Discovery | volume = 1 | pages = 224–233 |date=November 2020 |doi = 10.1158/2643-3230.BCD-20-0011 | doi-access = free }}</ref><ref name=":2">{{Cite journal|title = Lymphoid and myeloid lineage commitment in multipotent hematopoietic progenitors|journal = Immunological Reviews|date = 2010-11-01|issn = 1600-065X|pmc = 2975965|pmid = 20969583|pages = 37–46|volume = 238|issue = 1|doi = 10.1111/j.1600-065X.2010.00963.x|first = Motonari|last = Kondo}}</ref> Τα HSCs firstπρώτα differentiateδιαφοροποιούνται intoσε κύτταρα [[multipotentπολυδύναμος progenitorπρογονός]] (MPP) cells, thenστη [[commonσυνέχεια lymphoidσε progenitor]] (CLP) cells.<ref name=":2" /> From here, their development into B cells occurs in several stages (shown in image to the right), each marked by variousκύτταρα [[geneκοινής expression]]λεμφοειδούς patterns and [[Antibody|immunoglobulinπρογόνου]] [[Immunoglobulin heavy chain|H chain]] and [[Immunoglobulin light chain|L chain]] [[Locus (geneticsCLP)|gene loci]] arrangements, the latter due to B cells undergoing [[V(D)J recombination]] as they develop.<ref name=":3">{{Cite journal|title = Central B-Cell Tolerance: Where Selection Begins|journal = Cold Spring Harbor Perspectives in Biology|date = 2012-04-01|issn = 1943-0264|pmc = 3312675|pmid = 22378602|pages = a007146|volume = 4|issue = 4|doi = 10.1101/cshperspect.a007146|first1 = Roberta|last1 = Pelanda|first2 = Raul M.|last2 = Torres}}</ref>

B cells undergo two types of selection while developing in the bone marrow to ensure proper development, both involving B cell receptors (BCR) on the surface of the cell. Positive selection occurs through antigen-independent signaling involving both the pre-BCR and the BCR.<ref name=":4">{{Cite journal|title = The pre-B cell receptor checkpoint|last1 = Martensson|first1 = Inga-Lill|date = 2010|journal = FEBS Letters|volume = 584|issue = 12|pages = 2572–9|doi = 10.1016/j.febslet.2010.04.057|pmid = 20420836|last2 = Almqvist|first2 = Nina|last3 = Grimsholm|first3 = Ola|last4 = Bernardi|first4 = Angelina|s2cid = 43158480}}</ref><ref name=":5">{{Cite journal|title = B lymphocytes: how they develop and function|journal = Blood|date = 2008-09-01|issn = 0006-4971|pmc = 2518873|pmid = 18725575|pages = 1570–1580|volume = 112|issue = 5|doi = 10.1182/blood-2008-02-078071|first1 = Tucker W.|last1 = LeBien|first2 = Thomas F.|last2 = Tedder}}</ref> IfΕάν theseαυτοί receptorsοι doυποδοχείς notδεν bindσυνδέονται toμε theirτο [[Ligand (biochemistry)|ligandβιοχημεία]], B| cells do not receive the proper signals and cease to develop.<ref name=":4" /><ref name=":5" /> Negative selection occurs through the binding of self-antigen with the BCR; If the BCR can bind strongly to self-antigen, then the B cell undergoes one of four fates: [[clonal deletionσύνδεσμος]], [[receptor editing]]τους, [[Clonalτα anergy|anergy]],Β orκύτταρα ignoranceδεν (Bλαμβάνουν cellτα ignoresκατάλληλα signalσήματα andκαι continuesπαύουν development).<refνα name=":5" /> This negative selection process leads to a state of [[central tolerance]], in which the mature B cells do not bind self antigens present in the bone marrowαναπτύσσονται.<ref name=":3" />