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(Created page with "<span style="color:navy">'''''DETAILS'''''</span> CD38 helps mobilise intracellular calcium to activate a wide array of cell functions. In haematological cell types CD38 it is widely expressed by lymphoid cells )B, T and NK) as well as myeloid precursor cells and mature myeloid cells. It has particular diagnostic importance for lymphocytes where CD38 expression is acquired as stem cells commit to B-cell lineage, then is lost as mature B cells emerge from bone marrow be...")
 
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<span style="color:navy">'''''DETAILS'''''</span>


CD38 helps mobilise intracellular calcium to activate a wide array of cell functions. In haematological cell types CD38 it is widely expressed by lymphoid cells )B, T and NK) as well as myeloid precursor cells and mature myeloid cells. It has particular diagnostic importance for lymphocytes where CD38 expression is acquired as stem cells commit to B-cell lineage, then is lost as mature B cells emerge from bone marrow before being re-acquired at the time of plasma cell differentiation.
<div style="background-color: #E0EEEE; {{round corners}} padding: 2em 2em; margin-right: 5px;">




<span style="color:navy">'''What is its diagnostic role?'''</span>  
:<span style="color:navy">'''Summary'''</span>


The wide expression of CD38 limits its diagnostic value except in very specific circumstances:
:A pan B-cell marker with relatively high specificity for the identification of B-lineage. CD79a is expressed initially in cytoplasm of early B cells, before appearing on the membrane at the time heavy chains of immunoglobulin become expressed. 
*The co-expression of CD38 with CD138 can identify normal or neoplastic plasma cells
*Expression of CD38 in chronic lymphocytic leukaemia (>20% of cells) may associated with poorer outcome


</div>
:<span style="color:navy">'''Other relevant information'''</span>
CD79a expression is recognised on some AML and T-ALL cases so caution should be exercised particularly where other features are atypical. Like CD19, expression of CD79a is more often associated with aml that has t 8;21 translocation though less common
<span style="color:navy">'''Normal expression and function'''</span>
CD79a associates with CD79b and the immunoglobulin chains form part of the B-cell receptor (BCR). CD79a and CD79b each mediate intracellular signalling. However the two chains are expressed slightly differently in B cells - CD79a is a more lineage-specific marker than CD79b and expression is acquired at a very early stage of B-lymphocyte formation. CD79a is expressed initially in cytoplasm before appearing on the membrane of mature cells, persisting until plasma cell differentiation when it is progressively lost. 
<span style="color:navy">'''Diagnostic role'''</span>
*CD79a is a reliable marker of B-lymphocyte lineage with low levels of aberrant expression; it is more specific for B-cell lineage than CD19 or CD20, although it may rarely be expressed on other cell lineages.
*in ALL expression of CD79a is acquired in the cytoplam at an early stage of B-lineage commitment making it useful for identification of more primitive cases of ALL
*Expression is then retained on the cell surface through at later differentiation uuntil plasma cell differentiation where about half of cases of myeloma expressing CD79A strongly and a further proportion have weak expression. 


<span style="color:navy">'''Other relevant information:'''</span> CD38 is a therapeutic target, daratumumab is a monoclonal antibody which binds to CD38 and is used in the treatment of myeloma.




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<span style="color:navy">'''''SUMMARY TABLES'''''</span>
<span style="color:navy">'''''SUMMARY TABLES'''''</span>


{| class=wikitable style="text-align: center; width: 800px;"


<span style="font-size:90%">'''Note''' The colour and % refer to the proportion of cases expressing the marker. Additional comments on strength, or site of expression (if relevant) are given below the table. For full details of key click [[Key to marker expression table|here]]. For further information about a particular disease state click <<span style="color:blue>'''I'''</span>> adjacent to the condition name</span>
{| class=wikitable style="text-align: center; font-size:80%; width: 100%; height 20px;"
|-
!colspan="8"|'''Expression in primitive cell types'''</font>
|- <span style="font-size:70%">
!AML!!CMML !!B ALL !!BL ||T ALL !!ETP ALL !!MPAL ||Hgn</span>
|-<span style="font-size:70%">
|style="width: 12.5%; background: #66e0ff; color:black"|5-20%*
|style="width: 12.5%; background: #E6FAFF; color:black"|<5%
|style="width: 12.5%; background: #004466; color:white"|80-100%**
|style="width: 12.5%; background: #004466; color:white"|80-100%
|style="width: 12.5%; background: #66e0ff; color:black"|5-20%***
|style="width: 12.5%; background: #E6FAFF; color:black"|<5%
|style="width: 12.5%; background: #00b8e6; color:black"|20-40%
|style="width: 12.5%; background: #004466; color:white"|80-100%
|-
|-
!colspan="8"|Expression of CD38 by primitive lymphoid cells: ALL and haematogones
|}
|-  
 
! pro-B ALL !! early pre-B ALL !!pre-B ALL!! B-ALL !!pro-T ALL !!mature-T ALL !!AML !!Haematogones
<span style="font-size:90%">'''Notes:''' ''*'' expression is more frequent in t(8;21) mutation, ''**'' cytoplasmic expression is more frequent in early forms with surface expression acquired during maturation, ''***'' expression in T-ALL is infrequent but recognised </span>
 
 
{| class=wikitable style="text-align: center; font-size:80%; width: 100%; height 20px;"
|-
|-
|style= "width: 100px; height: 20px; background: #006699; color:white"|
!colspan="8"|'''Expression in mature B cell neoplasms'''
|style="width: 100px; background: #006699; color:white"|
|- <span style="font-size:70%">
|style="width: 100px; background: #006699; color:white"|
! CLL !! MCL !!FL!! MZL !! HCL !! DLBCL || LPL !! PCL
|style="width: 100px; background: #006699; color:white"|
|-<span style="font-size:70%">
|style="width: 100px; background: #006699; color:black"|
|style="width: 12.5%; background: #004466; color:white"|80-100%
|style="width: 100px; background: #006699; color:black"|
|style="width: 12.5%; background: #004466; color:white"|80-100%
|style="width: 100px; background: #00b8e6; color:white"|*
|style="width: 12.5%; background: #004466; color:white"|80-100%
|style="width: 100px; background: #004466; color:white"|stg
|style="width: 12.5%; background: #004466; color:white"|80-100%
|style="width: 12.5%; background: #004466; color:white"|80-100%
|style="width: 12.5%; background: #004466; color:white"|80-100%
|style="width: 12.5%; background: #004466; color:white"|80-100%
|style="width: 12.5%; background: #006699; color:white"|40-80%*
|-
|-
|}
|}
<span style="font-size:80%">''* low expression correlates with subtype e.g. APML''</span>


{| class=wikitable style="text-align: center; width: 800px; height 20px;"
<span style="font-size:90%">'''Notes:''' ''*'' expression in myleoma is variable but frequently observed </span>
 
 


{| class=wikitable style="text-align: center; font-size:80%; width: 62.4%; height 40px;"
|-
|-
!colspan="8"|Expression of CD38 by mature B cells: B-lymphoproliferative disorders
!colspan="7"|'''Expression in mature T cell neoplasms*'''
|-  
|-  
! CLL !! MCL !!FL!! HCL !!HCv !!MZL!!LPL!!PCL
! ATLL !! CTCL/Sezary !! T-PLL !! T-LGL !! NK-LGL
|-
|-
|style= "width: 100px; background: #00b8e6; color:black"|*
|style="width: 14.25%; background: #E6FAFF; color:black"|<5%
|style="width: 100px; background: #004466; color:white"|
|style="width: 14.25%; background: #E6FAFF; color:black"|<5%
|style="width: 100px; background: #004466; color:white"|**
|style="width: 14.25%; background: #E6FAFF; color:black"|<5%
|style= "width: 100px; background: #00b8e6; color:white"|
|style="width: 14.25%; background: #E6FAFF; color:black"|<5%
|style= "width: 100px; background: #00b8e6; color:white"|
|style="width: 14.25%; background: #E6FAFF; color:black"|<5%
|style="width: 100px; background: #004466; color:white"|
|style="width: 100px; background: #006699; color:white"|
|style="width: 100px; background: #004466; color:white"|stg/mod
|-
|-
|}
|}
<span style="font-size:80%">''*May indicate adverse prognostic when present on more than 20% of cells''</span>


<span style="font-size:80%">''**May be weak''</span>


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Latest revision as of 21:44, 4 July 2023


Summary
A pan B-cell marker with relatively high specificity for the identification of B-lineage. CD79a is expressed initially in cytoplasm of early B cells, before appearing on the membrane at the time heavy chains of immunoglobulin become expressed.



Other relevant information

CD79a expression is recognised on some AML and T-ALL cases so caution should be exercised particularly where other features are atypical. Like CD19, expression of CD79a is more often associated with aml that has t 8;21 translocation though less common


Normal expression and function

CD79a associates with CD79b and the immunoglobulin chains form part of the B-cell receptor (BCR). CD79a and CD79b each mediate intracellular signalling. However the two chains are expressed slightly differently in B cells - CD79a is a more lineage-specific marker than CD79b and expression is acquired at a very early stage of B-lymphocyte formation. CD79a is expressed initially in cytoplasm before appearing on the membrane of mature cells, persisting until plasma cell differentiation when it is progressively lost.


Diagnostic role

  • CD79a is a reliable marker of B-lymphocyte lineage with low levels of aberrant expression; it is more specific for B-cell lineage than CD19 or CD20, although it may rarely be expressed on other cell lineages.
  • in ALL expression of CD79a is acquired in the cytoplam at an early stage of B-lineage commitment making it useful for identification of more primitive cases of ALL
  • Expression is then retained on the cell surface through at later differentiation uuntil plasma cell differentiation where about half of cases of myeloma expressing CD79A strongly and a further proportion have weak expression.



SUMMARY TABLES


Note The colour and % refer to the proportion of cases expressing the marker. Additional comments on strength, or site of expression (if relevant) are given below the table. For full details of key click here. For further information about a particular disease state click <I> adjacent to the condition name


Expression in primitive cell types
AML CMML B ALL BL T ALL ETP ALL MPAL Hgn
5-20%* <5% 80-100%** 80-100% 5-20%*** <5% 20-40% 80-100%

Notes: * expression is more frequent in t(8;21) mutation, ** cytoplasmic expression is more frequent in early forms with surface expression acquired during maturation, *** expression in T-ALL is infrequent but recognised


Expression in mature B cell neoplasms
CLL MCL FL MZL HCL DLBCL LPL PCL
80-100% 80-100% 80-100% 80-100% 80-100% 80-100% 80-100% 40-80%*

Notes: * expression in myleoma is variable but frequently observed


Expression in mature T cell neoplasms*
ATLL CTCL/Sezary T-PLL T-LGL NK-LGL
<5% <5% <5% <5% <5%


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