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CD5

Characteristics

The CD5 antigen is a 67 kDa transmembrane glycoprotein expressed on the surface of  practically all mature human T-cells (Fig. 1) (about 10% of CD4+ T-cells being CD5 negative). In immature (CD34+) T-cells, CD5 is weakly expressed, the intensity of expression increaing with maturation. CD5 is also expressed in a small subset of normal human B-cells (20% of B-cells in the peripheral blood, scattered cells in the lymph node mantle zone). The CD5+ cells are probably involved in B-T interaction and their ligand is CD72 which is expressed on all B cells. It appears that CD5+ B-cells on activation primarily produce IgM. They also produce more autoantibodies than normal CD5 negative B-cells. Thus, the CD5+ B-cell population is expanded in rheumatoid arthrititis and systemic lupus erythematosus.

 

Neoplasms

CD5 is detected in most T-cell lymphomas (Fig. 2A) and leukaemias, including 75% of peripheral T-cell lymphomas and 85% of T-ALL cases. Lack of CD5 in the latter signifies a worse prognosis.

Among B-cell lymphomas, more explicit CD20+ small-cell lymphomas, small lymphocytic lymphoma and mantle cell lymphoma are CD5+ (Fig. 2C), whereas follicular lymphoma, marginal zone lymphoma and lymphoplasmacytoid lymphoma are CD5 negative (Fig. 2B). CD5 is detected in 5% of acute myeloid leukaemias.

CD5 has been detected in some cases of thymic carcinoma and atypical thymoma. Other carcinomas are CD5 negative.

 

Application

Classification of small B-cell lymphomas, see the algorithm to the right (Hsi & Tubbs 1999).

Prognostication of T-ALL. Identification of large cell lymphoma (CD5 negative) supervening a CD5+ small lymphocytic lymphoma. Differentiation between reactive CD5+ T-cell infiltration and CD5 negative T-cell neoplasm.

Identification of thymic carcinoma.

CyD1: cyclin D1, SLL: small lymphocytic lymphoma,

MCL: mantle cell lymphoma, FCL: follicular lymphoma,

MZL: marginal cell lymphoma,

LPL: lymphoplasmacytoid lymphoma

Visualization

Clone 4C7 is the most commonly used mAb for detecting CD5. However, CD5 can be difficult to detect in formalin fixed tissue without an optimized protocol (which includes HIER in an alkaline buffer).

The clone Leu-1, originally designated for unfixed material, can be used for formalin fixed material using HIER with Target Retrieval Solution (TRS) pH 6.1 (S1700, Dako).

CD5+ B-cells and B-cell lymphomas generally express less CD5 than T-cells. Thus, a positive staining of the latter may not be a sufficient internal control.

Control tissue: Tonsil. Apart from strongly stained T-cells, a weaker but distinct membranous staining of about 20% of the mantle zone B-cells should be revealed.

 

Assessments

Run 3 2000

Run 8 2003

Run 17 2006

 

Selected references

Arber DA, Weiss LM: CD5 A review. Applied immunohistochemistry 1995; 3:1-22.

De Leon ED, Alkan S, Huang JC, et al.: Usefulness of an immunohistochemical panel in paraffin-embedded tissues for the differentiation of B-cell non-Hodgkin’s lymphomas of small lymphocytes. Modern Pathology 1998;11:1046-1051.

Hardy RR. CD5 B cells, a fetal B cell lineage. Advances in Immunology 1994;55:297-339.

Hsi ED, Tubbs RR: Imunophenotyping as an adjunct in the diagnosis of small B-cell lymphomas. Pathology Case Reviews. 1999;4:242-249.
HH/MV/AS

Last update 30-06-2006