CD1a

Summary

A T cell marker that has value for demonstrating T-lineage in specific diagnostic circumstances

Background

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, then is lost in mature T cells.

Diagnostic Use

• A marker of early T-lineage
• CD1A us useful in the identification of some cases of T-all and for showing T lineage in MPAL
• Absence of CD1A staining may be helpful in recognition of ETP-ALL
• Aberrant expression of CD1A is recognised to occur at both B cells and myeloid cells

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