Changes

|sublink2 =Adaptive Immune System - WikiBlood

|sublink2 =Adaptive Immune System - WikiBlood

|subtext2 =ADAPTIVE IMMUNE SYSTEM

|subtext2 =ADAPTIVE IMMUNE SYSTEM

|sublink3=Lymphocytes - WikiBlood

|sublink3=Lymphocytes

|subtext3=LYMPHOCYTES

|subtext3=LYMPHOCYTES

|pagetype =Blood

|pagetype =Blood

==Introduction==

==Introduction==

<p>Mature [[Lymphocytes - WikiBlood#B cells|B cells]] that undergo stimulation by an antigen undergo class switching, and differentiate into either [[#Plasma cells|plasma]] or [[#Memory cells|memory]] cells. </p>

<p>Mature [[Lymphocytes#B cells|B cells]] that undergo stimulation by an antigen undergo class switching, and differentiate into either [[#Plasma cells|plasma]] or [[#Memory cells|memory]] cells. </p>

<p>In the paracortex region of [[Lymph Nodes - Anatomy & Physiology|lymph nodes]] binding to MHC II and the presence of Il-4 produced by [[Lymphocytes - WikiBlood#Helper CD4+|CD4⁺ T cells]] (Th2 type) causes [[Lymphocytes - WikiBlood#B cells|B cells]] to differentiate. Most [[Lymphocytes - WikiBlood#B cells|B cells]] become [[#Plasma cells|plasma cells]], however small number become [[#Memory cells|memory cells]] .</p>

<p>In the paracortex region of [[Lymph Nodes - Anatomy & Physiology|lymph nodes]] binding to MHC II and the presence of Il-4 produced by [[Lymphocytes#Helper CD4+|CD4⁺ T cells]] (Th2 type) causes [[Lymphocytes#B cells|B cells]] to differentiate. Most [[Lymphocytes#B cells|B cells]] become [[#Plasma cells|plasma cells]], however small number become [[#Memory cells|memory cells]] .</p>

==Antigen Presentation by Follicular Dendritic Cells==

==Antigen Presentation by Follicular Dendritic Cells==

Follicular dendritic cell are present in the follicles. They absorb the whole of the antigen onto their surface to present to [[Lymphocytes - WikiBlood#B cells|B cells]] to stimulate an immune response.

Follicular dendritic cell are present in the follicles. They absorb the whole of the antigen onto their surface to present to [[Lymphocytes#B cells|B cells]] to stimulate an immune response.

==Plasma cells==

==Plasma cells==

===Function===

===Function===

[[Image:B-cell-Ab.jpg|thumb|right|150px|Plasma cell antibody production - B. Catchpole, RVC 2008]]

[[Image:B-cell-Ab.jpg|thumb|right|150px|Plasma cell antibody production - B. Catchpole, RVC 2008]]

<p>Plasma cells produce immunoglobulins/antibodies (thousands a second). The immunoglobulin binding specificity is identical to the binding specificity of the BCR on the [[Lymphocytes - WikiBlood#B cells|B cell]] that the cell has differentiated from. This means that when a [[Lymphocytes - WikiBlood#B cells|B cell]] has a BCR that can effectively bind to an antigen the immunoglobulins produced by the plasma cell can bind to that antigen.</p>

<p>Plasma cells produce immunoglobulins/antibodies (thousands a second). The immunoglobulin binding specificity is identical to the binding specificity of the BCR on the [[Lymphocytes#B cells|B cell]] that the cell has differentiated from. This means that when a [[Lymphocytes#B cells|B cell]] has a BCR that can effectively bind to an antigen the immunoglobulins produced by the plasma cell can bind to that antigen.</p>

<p>Although they can live for months most plasma cells only live for a few days and do not replicate in this time.</p>

<p>Although they can live for months most plasma cells only live for a few days and do not replicate in this time.</p>

Interaction of a B-cell with antigen results in clonal expansion, as does activation by T-cells. The majority of B-cell clones mature into plasma cells. Plasma cells are found in the splenic [[Spleen - Anatomy & Physiology#Red Pulp|red pulp]], [[Lymph Nodes - Anatomy & Physiology#Lymph Nodes|lymph node medulla]] and [[Bone Marrow - Anatomy & Physiology|bone marrow]]. Plasma cells are the terminal differentiation state of B-cells. They migrate to the medullary cords where their whole function is to secrete antibody.

Interaction of a B-cell with antigen results in clonal expansion, as does activation by T-cells. The majority of B-cell clones mature into plasma cells. Plasma cells are found in the splenic [[Spleen - Anatomy & Physiology#Red Pulp|red pulp]], [[Lymph Nodes - Anatomy & Physiology#Lymph Nodes|lymph node medulla]] and [[Bone Marrow - Anatomy & Physiology|bone marrow]]. Plasma cells are the terminal differentiation state of B-cells. They migrate to the medullary cords where their whole function is to secrete antibody.

===Class switching===

===Class switching===

<p>Initially plasma cell produce [[Immunoglobulin M - WikiBlood|IgM]] however this is not always the most appropriate Ig to be produced and therefore stimulation by [[Lymphocytes - WikiBlood#Helper CD4+|T cells]] and interleukins causes the plasma cells to undergo class switching to produce different classes of Ig.

<p>Initially plasma cell produce [[Immunoglobulin M - WikiBlood|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 Ig.

*In mucosal B cells plasma cells CD40 interaction (with Th2 CD40L) and Il-10 stimulates class switching to [[Immunoglobulin A - WikiBlood|IgA]]

*In mucosal B cells plasma cells CD40 interaction (with Th2 CD40L) and Il-10 stimulates class switching to [[Immunoglobulin A - WikiBlood|IgA]]

*[[Eosinophils - WikiBlood|Eosinophils]] produce Il-13 which promotes class switching to [[Immunoglobulin E - WikiBlood|IgE]]</p>

*[[Eosinophils - WikiBlood|Eosinophils]] produce Il-13 which promotes class switching to [[Immunoglobulin E - WikiBlood|IgE]]</p>