CD5

CD5 is a 67 kDa glycoprotein.

Antibody clone NCL-CD5-4C7 is effective on paraffin-embedded tissue³. The Leu1 antibody will also stain paraffin-embedded tisue after antigen retrieval and tyramine-enhanced detection.

Immunohistochemical expression

• Thymocytes

• The majority of T-cells

• A small subset of lymphocytes (B-1 lymphocytes) which may increase in number in auto-immune conditions.

Diagnostic utility

• T-cell lymphomas, including most T-LBL and some ALCL. Aberrant loss of expression may occur in T-cell lymphomas and may help to distinguish them from reactive T-cell proliferations². Loss of CD5 may occur in extranodal T/NK cell lymphoma, intestinal T-cell lymphoma, hepatosplenic T-cell lymphoma and some cutaneous T-cell lymphomas.

• Expressed in 85% of T-ALL/T-LBL

• 3-10% of AML

• Expressed by > 90% of B-CLL, including transformed CLL

• mantle cell lymphoma

• almost all other low grade B cell lymphomas are CD5 negative

• some diffuse large B cell lymphomas are CD5-positive, possible associated with a worse prognosis.

• Differentiation of T-cell lymphoma (CD5+) from NK cell lymphoma (CD5-), for example in nasal lymphomas⁵.

• Pomplun found CD5 possibly useful in distinguishing thymic carcinomas from pulmonary carcinomas¹. Several other studies have reported that CD5 is a promising marker for thymic carcinoma. Other epithelial neoplasms generally do not express this marker. Of note, the sensitivity and specificity depend on the clone of the anti-CD5 antibody: clone 54/F6 is less sensitive but more specific⁴.

References

¹ S Pomplun. Immunohistochemical markers in the differentiation of thymic and pulmonary neoplasms. Abstract 158, Pathological Society of Great Britain and Ireland January 2001.

² Bakels, V., van Oostveen, J.W., van der Putte, S.C., Meijer, C.J. and Willemze, R. Immunophenotyping and gene rearrangement analysis provide additional criteria to differentiate between cutaneous T-cell lymphomas and pseudo- T-cell lymphomas. Am J Pathol 1997;150:1941-9.

³ Leong A S-Y, Cooper K and Leong FJ W-M. Manual of diagnostic antibodies for immunohistology. 2nd edition, 2003

⁴ Pan, C. C., P. C. Chen, et al. (2003). "Expression of calretinin and other mesothelioma-related markers in thymic carcinoma and thymoma." Hum Pathol 34(11): 1155-62.

⁵ Kitamura A, Yamashita Y, Hasegawa Y, et al. Primary lymphoma arising in the nasal cavity among Japanese. Histopathology 2005; 47:523-32

©SMUHT/PW Bishop