CD45RO (UCHL1, A6, OPD4)

CD45RO is an isoform of CD45 that is found on thymocytes and T-cells. Antibodies UCHL1 and A6 are effective on paraffin-embedded tissue2. CD3 is a more specific T-cell marker.

Immunohistochemical expression

• 90% of cortical thymocytes

• 50% of medullary thymocytes

• 50-70% of CD2-/CD3+ peripheral lymphocytes

• 90% of peripheral T-cell lymphomas

• 80% of precursor T-cell lymphoblastic lymphomas

• mycosis fungoides

• anaplastic large cell lymphomas may be positive for CD45RO while being negative for other T-cell markers

• rarely with benign B lymphocytes

• about 10% of B-cell lymphomas, particularly AIDS-related large cell lymphomas

• mature monocytes and macrophages with UCHL11 but not OPD4

• granulocytes1 and myeloid sarcoma

• 30% of Reed-Sternberg cells in classical Hodgkin lymphoma

• some intestinal intra-epithelial lymphocytes are CD 45RO negative

• epithelial cells may show diffuse cytoplasmic staining

Diagnostic utility

• differentiation of low grade T cell from low grade B cell lymphoma: sensitivity 95%, specificity 95%

• differentiation of high grade T cell from high grade B cell lymphoma: sensitivity 80%, specificity 85%

See: comparison of sensitivities and specificities of T and B cell markers

References

1M Steward et al. Production and characterization of a new monoclonal antibody effective in recognizing the CD3 T-cell associated antigen in formalin-fixed embedded tissue. Histopathology 1997;30:16-22.

2Leong A S-Y, Cooper K and Leong FJ W-M. Manual of diagnostic antibodies for immunohistology. 2nd edition, 2003

©SMUHT/PW Bishop