CD45: Difference between revisions

Latest revision as of 16:56, 13 July 2023

Summary

CD45 is expressed by almost all mature or maturing leucocytes, often called: "leukocyte common antigen".

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

Background

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.

Diagnostic Use

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.

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)

Population A debris, platelets, unlysed red cells
Population B granulocytic cells
Population C monocytic cells
Population D lymphoid cells
Population E blast cells

@@ Line 5: / Line 5: @@
 :<span style="color:navy">'''Summary'''</span>
-:CD45 is expressed by almost all mature or maturing leucocytes: hence the name leukocyte common antigen.
+:CD45 is expressed by almost all mature or maturing leucocytes, often called: "leukocyte common antigen".
-: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 markers (particularly light scatter parameters) CD45 can be used to make a provisional identification of the different leukocyte types, allow different populations to be analysed individually.
+: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'''
-:Most frequently therefore the use of this antigen is for '''CD45 gating'''
@@ Line 17: / Line 15: @@
 :<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 typically highest in cells actively involved in immune proceses lymphocytes and monocytes and lower in other populations including blast cells.
+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">'''Diagnostic Use'''</span>
-When combined with side scatter in two-dimensional dot plots CD45 expression can allow different leukocyte types to be separately identified and analysed. This can be very useful for analysis of individual populations of interest e.g. blast cells; lymphocytes etc.
+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.
-Some cell types - particularly plasma cells are not easy to identify using CD45 gating since their expression of CD45 can be variable even within a single case.
-cd45 gating
-cd45boxedpops.png
-A typical flow plot illustrating the position of different cell types in a normal individual
-y-axis side scatter of light:light is scattered at an angle to cells ssc differently according to granularity cytoplasmic outline or nuclear complexity
-x-axis cd45 expression log scale the level of cd45 expression is variably different normal or malignant cell types
-population a: nucleated red cells others & debris   these round agranular cells scatter very little light and do not express cd45. debris and platelet aggregates may also appear here; in such cases the cell populations and distribution may indicate poor sample quality.  note  that blast cells particularly all blasts non-haematopoietic tumours or plasma cells may appear in this area.
-population b: mature and maturing granulocytes  high granularity irregular outline and nuclear complexity all cause high light scatter cd45 expression is moderate but increases with maturity. the many different forms with differing ssc and cd45 mean that the population forms a spread cloud.  note  the position of the cloud may be altered in myelodysplasia where cell form is changed or more primitive forms are present
+'''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.
+----
-population c   monocytes  the size and nuclear irregularity give these cells light scatter properties intermediate between lymphocytes and granulocytes. the requirement to engage in immune responses means that they have high cd45 expression generally a little lower than that of lymphocytes .  note  abnormal or more primitive forms e.eg. cmml may have lower cd45 expression
+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)
-population d   lymphocytes & basophils   smaller cells - all with relatively low light scatter which seems odd for basophils but is true . all engage in immune responses and cytokine interactions mediated by their high cd45 activity.  note  that lymphocytes may have varied cd45 expression with weaker expression on b-cells and particularly precursor b-cells haematogones . neoplastic cells may have weak e.eg.ecll or strong e.eg. hcl expression of cd45 ---- file cd45wksscwk.epng left 200px caption
+<gallery mode="nolines" widths="300px" heights="300px" border="1px" >
+file:CD45_populations.jpg|link={{filepath:CD45_populations.jpg}}
+</gallery>
-population e   blasts and maturing precursor cells  primitive blast cells have low and sometimes absent cd45 expression the cells tend to have round nuclei and few granules so have low light scatter but this can vary considerably according to their differentiation.  note  normal maturing cells in this area are few in number and have a wide range of light scatter reflecting their variable maturation. blast cells in leukaemia may form a tighter population in greater number but may also vary in ssc depending on their maturation.
+<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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CD45: Difference between revisions

From haematologyetc.co.uk

Latest revision as of 16:56, 13 July 2023