CD45

Summary

CD45 is expressed by almost all mature or maturing leucocytes: hence the name 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.

Most frequently therefore the use of this antigen is for CD45 gating

Background

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.

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. 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.

Image: typical positions of cell populations using CD45 gating

Links: Examples of the position for different malignant populations using CD45 plots

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