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[[file:LPL.jpg|200px|link=LPL.jpg]]  




:<span style="color:navy">'''Summary'''</span>
<span style="color: navy>'''Background to flow cytometric diagnosis'''</span>


:CD45 is expressed by almost all mature or maturing leucocytes, often called: "leukocyte common antigen".  
These cells share features of mature B cell differentation with features of early plasma cell differentiation and may have mixed populations with features of each. Where either B-cell differentiation or plasma cell features predominate this can make the diagnosis difficult.


:Usefully, the level of expression of CD45 differs according to both the cell type it is expressed on, and the maturation stage of that cell. Generally the expression for any cell type is quite consistent. This means that, when combined with other flow cytometry parameters (typically side-scatter of light) CD45 can be used to identify and select different leukocyte populations that can then be analysed individually: '''CD45 gating''' 




<div style="width: 95%; overflow: auto; border: 1px solid navy; font-size:100%">
{| class="wikitable" style="color:black; background-color:#ffffff;" cellpadding="5"
!colspan="4" style = "font-size:110%; color: navy; text-align:center; background:#DEE0DE;"|'''Immunophenotype of LPL'''
|-
!colspan="4" style = "font-size:90%; background:#DAE8F2"|Major markers useful in CLL diagnosis
|-
|colspan="1" style = "font-size:80%; width: 4%; |'''Marker'''
|colspan="1" style = "font-size:80%; width: 8%; |'''Freq'''
|colspan="1" style = "font-size:80%; width: 8%; |'''Level'''
|colspan="1" style = "font-size:80%; width: 80%; |'''Comment'''
|-
|colspan="1" style = "font-size:90%; color:black;" |CD19
|colspan="1" style = "background:#006699;"|
|colspan="1" style = "font-size:80%;"|-
|colspan="1" style = "font-size:84%;"|Generally CD19 will be expressed
|-
|colspan="1" style = "width: 4%; font-size:90%; color:black;" |κ/λ
|colspan="1" style = "width: 8%; background:#006699;"|
|colspan="1" style = "font-size:80%; width: 8%; |
|colspan="1" style = "font-size:80%;"|Light chain retriction usually detected
|-
|colspan="1" style = "font-size:90%; color:black;" |CD5
|colspan="1" style = "background:#66e0ff;"|
|colspan="1" style = "font-size:80%;"|-
|colspan="1" style = "font-size:80%;"|Uncommon but seen in some cases
|-
|colspan="1" style = "font-size:90%; color:black;" |CD23
|colspan="1" style = "background:#00b8e6;"|
|colspan="1" style = "font-size:80%;"|-
|colspan="1" style = "font-size:84%;"|Infrequent but reported
|-
|colspan="1" style = "font-size:90%; color:black;" |CD79b
|colspan="1" style = "background:#006699;"|
|colspan="1" style = "font-size:80%;"|-
|colspan="1" style = "font-size:84%;"|Generally expressed
|-
|colspan="1" style = "font-size:90%; color:black;" |CD200
|colspan="1" style = "background:#66e0ff;"|
|colspan="1" style = "font-size:80%;"|-
|colspan="1" style = "font-size:84%;"|Detected infrequently
|-
|colspan="1" style = "font-size:90%; color:black;" |FMC7
|colspan="1" style = "background:#006699;"|
|colspan="1" style = "font-size:80%;"|
|colspan="1" style = "font-size:80%;"|Generally expressed
|-
!colspan="4" style = "font-size:90%; background:#DAE8F2"|Other relevant markers
|-
|colspan="1" style = "font-size:90%;" |CD10
|colspan="1" style = "background:#006699;"|
|colspan="1" style = "font-size:80%;"|-
|colspan="1" style = "font-size:84%;"|Expression may be seen
|-
|colspan="1" style = "font-size:90%;" |CD11C
|colspan="1" style = "background:#006699;"|
|colspan="1" style = "font-size:80%;"|-
|colspan="1" style = "font-size:84%;"|
|-
|colspan="1" style = "font-size:90%;" |CD20
|colspan="1" style = "background:#004466;"|
|colspan="1" style = "font-size:80%;"|-
|colspan="1" style = "font-size:84%;"|Expect expression
|-
|colspan="1" style = "font-size:90%; color:black;" |CD25
|colspan="1" style = "background:#66e0ff;"|
|colspan="1" style = "font-size:80%;"|-
|colspan="1" style = "font-size:84%;"|
|-
|colspan="1" style = "font-size:90%; color:black;" |CD38
|colspan="1" style = "background:#004466;"|
|colspan="1" style = "font-size:80%;"|-
|colspan="1" style = "font-size:84%;"|
|-
|colspan="1" style = "font-size:90%;" |CD43
|colspan="1" style = "background:#66e0ff;"|
|colspan="1" style = "font-size:80%;"|-
|colspan="1" style = "font-size:84%;"|
|-
|colspan="1" style = "font-size:90%;" |CD103
|colspan="1" style = "background:#E6FAFF;"|
|colspan="1" style = "font-size:80%;"|-
|colspan="1" style = "font-size:84%;"|
|-
|colspan="1" style = "font-size:90%;" |CD138
|colspan="1" style = "background:#66e0ff;"|
|colspan="1" style = "font-size:80%;"|-
|colspan="1" style = "font-size:84%;"|
|-
|}
</div>
</div>




:<span style="color:navy">'''Background'''</span>


CD45 is a transmembrane protein that de-phosphorylates signalling molecules associated with immunological receptors to change their activation state. Expression is therefore typically highest in cells actively involved in immune processes e.g. lymphocytes and monocytes and is lower in other populations including blast cells.
<span style="color:navy;font-size:80% ">'''Key to table: '''</span>


<span style="font-size:80% ">Key to colour code for expression frequency [[Key_to_marker_expression_table|Click for link]]</span>


:<span style="color:navy">'''Diagnostic Use'''</span>
<span style="font-size:80% ">Key to expression strength code and use [[Expression strength key|Click for link]]</span>


When combined with side scatter in two-dimensional dot plots CD45 expression can allow different leukocyte types to be separately identified and analysed (CD45 gating). This can be very useful for analysis of individual populations of interest e.g. blast cells; lymphocytes etc.


'''NOTE''' some cell types - particularly plasma cells are not easy to identify using CD45 gating since their expression of CD45 can be variable between cases and even within a single case.


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The appearance of CD45 plots varies with flow cytometer and also with laboratory preferences, however to illustrate how CD45 may be used to identify cells an example is given below: CD45 fluorescent intensity (log scale) on X-axis, Side scatter parameters linear scale on Y-axis. Cells then are separated according to the intensity of CD45 expression, but also according to side scatter parameters (irregularity of cytoplasm, nucleus, granularity etc) 
<gallery mode="nolines" widths="300px" heights="300px" border="1px" >
file:CD45_populations.jpg|link={{filepath:CD45_populations.jpg}}
</gallery>
<gallery mode="nolines" widths="200px" heights="240px" border="1px" >
file:CD45-PopA.jpg|'''Population A''' debris, platelets, unlysed red cells|link={{filepath:CD45-PopA.jpg}}
file:CD45-PopB.jpg|'''Population B''' granulocytic cells|link={{filepath:CD45-PopB.jpg}}
file:CD45-PopC.jpg|'''Population C''' monocytic cells|link={{filepath:CD45-PopC.jpg}}
file:CD45-PopD.jpg|'''Population D''' lymphoid cells|link={{filepath:CD45-PopD.jpg}}
file:CD45-PopE.jpg|'''Population E''' blast cells|link={{filepath:CD45-PopE.jpg}}
</gallery>
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Revision as of 17:02, 13 July 2023

LPL.jpg


Background to flow cytometric diagnosis

These cells share features of mature B cell differentation with features of early plasma cell differentiation and may have mixed populations with features of each. Where either B-cell differentiation or plasma cell features predominate this can make the diagnosis difficult.


Immunophenotype of LPL
Major markers useful in CLL diagnosis
Marker Freq Level Comment
CD19 - Generally CD19 will be expressed
κ/λ Light chain retriction usually detected
CD5 - Uncommon but seen in some cases
CD23 - Infrequent but reported
CD79b - Generally expressed
CD200 - Detected infrequently
FMC7 Generally expressed
Other relevant markers
CD10 - Expression may be seen
CD11C -
CD20 - Expect expression
CD25 -
CD38 -
CD43 -
CD103 -
CD138 -


Key to table:

Key to colour code for expression frequency Click for link

Key to expression strength code and use Click for link


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