CD22: Difference between revisions
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<span style="font-size:90%">'''Notes:''' | <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 bilineage disease </span> | ||
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<span style="font-size:90%">'''Notes:''' | <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> | ||
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! ATLL !! CTCL/Sezary !! T-PLL !! T-LGL !! NK-LGL | ! ATLL !! CTCL/Sezary !! T-PLL !! T-LGL !! NK-LGL | ||
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<span style="font-size:90%">'''Notes:''' | <span style="font-size:90%">'''Notes:''' Expression of CD22 is uncommon in mature T cell disorders </span> | ||
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Revision as of 15:31, 10 May 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 | Burkitt | T ALL | ETP ALL <I> | MPAL <I> | Hgns <I> |
| <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 bilineage disease
| 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