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(Created page with "CD22 expression is largely restricted to b cell lineage and expression is acquired at an early differentiation stage. *expression varies during mature b-cell development however the major value of CD22 lies in the identification of all based on high lineage-specificity and very early acquisition allowing the identification of pro-b all. normal expression and function CD22 is a membrane receptor that binds sialic acid containing glycans and expression is mostly rest...")
 
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CD22 expression is largely restricted to b cell lineage and expression is acquired at an early differentiation stage.
*expression varies during mature b-cell development however the major value of CD22 lies in the identification of all based on high lineage-specificity and very early acquisition allowing the identification of pro-b all. 


normal expression and function  
<div style="background-color: #E0EEEE; {{round corners}} padding: 2em 2em; margin-right: 5px;">
CD22 is a membrane receptor that binds sialic acid containing glycans and expression is mostly restricted to b cells where it is believed to be a negative regulator of activation. expression is developmentally related - first appearing in cytoplasm then on the surface in pre-b cells CD22 is fully expressed by mature b cells but lost on plasma cell differentiation. basophils express CD22. 


other relevant information 
as a result of its restricted expression CD22 has emerged as a therapeutic target in acute lymphoblastic leukemia all and other b cell disorders. 


diagnostic role 
:<span style="color:navy">'''Summary'''</span>
*its early cytoplasmic expression gives CD22 particular value in the detection of pro b-all diagnosis requires expression of two of the following three markers CD22 membrane or cytoplasm ; CD19 or CD79a. CD22 may not be uniformly expressed across the population with expression being seen on 60-90 of cells.
 
*in mature b cell neoplasms CD22 has relatively low expression in cll mcl and fcl but has markedly increased expression in hcl and related disorders.
:CD22 expression is largely restricted to B-lymphocytes
:The major value of CD22 lies in the identification of ALL based on high lineage-specificity and very early acquisition in cytoplasm followed by cell surface expression
 


----  summary tables 
1. expression by acute leukaemias and by haematogones file freqepng  pro-b all  link flow cytometry key file hiepng  early pre-b all  link flow cytometry key file hiepng  pre-b all  link flow cytometry key file hiepng  early b all  link flow cytometry key file rareepng  pro-t all  link flow cytometry key file rareepng  mature-t all  link flow cytometry key file rareepng  aml  link flow cytometry key file hiepng  haemato-gones  link flow cytometry key  *basophils are recognised to express CD22 
   
   
2. expression by b-lymphoproliferative disorders file hiepng frame  cll * link flow cytometry key file hiepng  pll**  link flow cytometry key file hiepng mcl  link flow cytometry key file hiepng  fl  * link flow cytometry key file hiepng  hcl**  link flow cytometry key file hiepng  hclv  link flow cytometry key file hiepng  mzl  link flow cytometry key file hiepng  lpl  link flow cytometry key file possepng  pcs  link flow cytometry key  *  typically weak  **  typically strong ----
</div>
 
 
 
<span style="color:navy">'''Normal expression and function'''</span>
 
CD22 is a membrane adhesion receptor whose expression is mostly restricted to B lymphocytes where it is believed to be a negative regulator of activation. Expression is developmentally related - first appearing in cytoplasm of pro-B cells then on the surface in pre-B cells. CD22 is fully expressed by mature-B cells, but is lost during plasma cell differentiation.
 
 
 
<span style="color:navy">'''Diagnostic role'''</span>
 
*Cytoplasmic expression of CD22 gives particular value in the detection of pro-B ALL where diagnosis requires expression at least two of three markers: CD22 (membrane or cytoplasm), CD19 or CD79a. CD22 may not be uniformly expressed across a cell population with expression often being seen on only 60-90 of cells
*in mature B cell neoplasms CD22 has relatively low expression in CLL, MCL and FL, but has high expression in HCL
 
 
 
   
 
<span style="color:navy">'''Other relevant information:'''</span>
 
Basophils express CD22  
 
 
----
 
 
 
<span style="color:navy">'''''SUMMARY TABLES'''''</span>
 
 
<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: #E6FAFF; color:black"|<5%
|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: #E6FAFF; color:black"|<5%
|style="width: 12.5%; background: #E6FAFF; color:black"|<5%
|style="width: 12.5%; background: #66e0ff; color:black"|20-40%
|style="width: 12.5%; background: #004466; color:white"|80-100%
|-
|}
 
<span style="font-size:90%">'''Notes:''' Expression of CD22 is a feature of B-lineage commitment that is not essential for diagnosis, but strongly suggests B lineage. Aberrant expression is uncomon and should suggest the possibility of MPAL </span>
 
 
{| class=wikitable style="text-align: center; font-size:80%; width: 100%; height 20px;"
|-
!colspan="8"|'''Expression in mature B cell neoplasms'''
|- <span style="font-size:70%">
! CLL !! MCL !!FL!! MZL !! HCL !! DLBCL || LPL !! PCL
|-<span style="font-size:70%">
|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: #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: #E6FAFF; color:black"|<5%
|-
|}
 
<span style="font-size:90%">'''Notes:''' The level of expression may vary both between and within cases of mature B cell neoplasm, but expression tends to be lost by mature plasma cells </span>
 
 
 
{| class=wikitable style="text-align: center; font-size:80%; width: 62.4%; height 40px;"
|-
!colspan="7"|'''Expression in mature T cell neoplasms*'''
|-
! ATLL !! CTCL/Sezary !! T-PLL !! T-LGL !! NK-LGL
|-
|style="width: 14.25%; background: #E6FAFF; color:black"|<5%
|style="width: 14.25%; background: #E6FAFF; color:black"|<5%
|style="width: 14.25%; background: #E6FAFF; color:black"|<5%
|style="width: 14.25%; background: #E6FAFF; color:black"|<5%
|style="width: 14.25%; background: #E6FAFF; color:black"|<5%
|-
|}
 
<span style="font-size:90%">'''Notes:''' Expression of CD22 is uncommon in mature T cell disorders </span>
 
----

Latest revision as of 21:39, 4 July 2023


Summary
CD22 expression is largely restricted to B-lymphocytes
The major value of CD22 lies in the identification of ALL based on high lineage-specificity and very early acquisition in cytoplasm followed by cell surface expression



Normal expression and function

CD22 is a membrane adhesion receptor whose expression is mostly restricted to B lymphocytes where it is believed to be a negative regulator of activation. Expression is developmentally related - first appearing in cytoplasm of pro-B cells then on the surface in pre-B cells. CD22 is fully expressed by mature-B cells, but is lost during plasma cell differentiation.


Diagnostic role

  • Cytoplasmic expression of CD22 gives particular value in the detection of pro-B ALL where diagnosis requires expression at least two of three markers: CD22 (membrane or cytoplasm), CD19 or CD79a. CD22 may not be uniformly expressed across a cell population with expression often being seen on only 60-90 of cells
  • in mature B cell neoplasms CD22 has relatively low expression in CLL, MCL and FL, but has high expression in HCL



Other relevant information:

Basophils express CD22



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% <5% 80-100% 80-100% <5% <5% 20-40% 80-100%

Notes: Expression of CD22 is a feature of B-lineage commitment that is not essential for diagnosis, but strongly suggests B lineage. Aberrant expression is uncomon and should suggest the possibility of MPAL


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% <5%

Notes: The level of expression may vary both between and within cases of mature B cell neoplasm, but expression tends to be lost by mature plasma cells


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

Notes: Expression of CD22 is uncommon in mature T cell disorders

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