Extra

CD1a

• a marker of early t-lineage that is useful for the identification of some cases of t-all expression is notably absent in etp-all

• CD1a may be useful to confirm t-lineage in some cases of mpal

details CD1a is structurally related to major histocompatibility complex proteins and is thought to mediate the presentation of lipid and glycolipid antigens. CD1a expression is absent on very early thymocytes but is acquired together with CD4 and CD8 as t cells develop in the thymus; expression precedes CD3. CD1a expression is lost at the mature t cell stage.

• in t-all CD1a is absent at early developmental stages pro-t and pre-t and is not expressed by etp-all early-t precursor all .
• CD1a is expressed by cortical t cells so expression of CD1a on leukaemic cells can contribute to a diagnosis of t-all or to the identification of t-lineage in mpal