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[[Image:B-cell immunity.jpg|thumb|right|250pxl|B-cell differentiation - B. Catchpole, RVC 2008]]
[[Image:B-cell immunity.jpg|thumb|right|250pxl|B-cell differentiation - B. Catchpole, RVC 2008]]
==Introduction==
==Introduction==
<p>Mature [[B cells]] that undergo stimulation by an antigen undergo class switching, and differentiate into either '''plasma''' or '''memory''' cells. </p>
<p>Mature [[B cells]] that undergo stimulation by an antigen undergo class switching, and differentiate into either '''plasma''' or '''memory''' cells. </p>
<p>In the paracortex region of the [[Lymph Nodes - Anatomy & Physiology|lymph node]] binding to [[Major_Histocompatability_Complexes#MHC_II|MHC II]] in the presence of IL-4 produced by the [[Lymphocytes#Helper CD4+|CD4<sup>+</sup> T cells]] (TH<sub>2</sub> type) causes the B cells to differentiate; most will become plasma cells, however a small number will become memory cells.</p>
<p>In the paracortex region of the [[Lymph Nodes - Anatomy & Physiology|lymph node]] binding to [[Major_Histocompatability_Complexes#MHC_II|MHC II]] in the presence of IL-4 produced by the [[Lymphocytes#Helper CD4+|CD4<sup>+</sup> T cells]] (T<sub>H</sub>2 type) causes the B cells to differentiate; most will become plasma cells, however a small number will become memory cells.</p>
Follicular dendritic cells present in the germinal centers of peripheral lymphoid organs can absorb intact antigen onto their surface to present to B cells to stimulate differentiation.
Follicular dendritic cells present in the germinal centers of peripheral lymphoid organs can absorb intact antigen onto their surface to present to B cells to stimulate differentiation.
===Class switching===
===Class switching===
<p>Initially plasma cell produce [[Immunoglobulin M|Immunoglobulin M (IgM)]] however this is not always the most appropriate Ig to be produced and therefore stimulation by [[Lymphocytes#Helper CD4+|T cells]] and interleukins causes the plasma cells to undergo class switching to produce different classes of Immunoglobulins.
<p>Initially plasma cell produce [[Immunoglobulin M|Immunoglobulin M (IgM)]] however this is not always the most appropriate Ig to be produced and therefore stimulation by [[Lymphocytes#Helper CD4+|T cells]] and interleukins causes the plasma cells to undergo class switching to produce different classes of Immunoglobulins.
*In mucosal B cells plasma cells CD40 interaction (with Th2 CD40L) and Il-10 stimulates class switching to [[Immunoglobulin A|IgA]]
*In mucosal B cells plasma cells CD40 interaction (with T<sub>H</sub>2 CD40L) and Il-10 stimulates class switching to [[Immunoglobulin A|IgA]]
*[[Eosinophils|Eosinophils]] produce Il-13 which promotes class switching to [[Immunoglobulin E|IgE]]</p>
*[[Eosinophils|Eosinophils]] produce Il-13 which promotes class switching to [[Immunoglobulin E|IgE]]</p>
<p>Plasma cells produced in the first immune response to an antigen are mainly of the class IgM whereas those produced from memory cells in the second immune response are mainly of the [[Immunoglobulin G|IgG]] class.</p>
<p>Plasma cells produced in the first immune response to an antigen are mainly of the class IgM whereas those produced from memory cells in the second immune response are mainly of the [[Immunoglobulin G|IgG]] class.</p>
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{{Jim Bee 2007}}
{{Jim Bee 2007}}
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[[Category:Lymphocytes|C]]
[[Category:Lymphocytes|C]]
[[Category:Adaptive Immune System]]
[[Category:Adaptive Immune System]]