CD4

CD4 is a co-receptor acting in the activation of T-helper cells by the MHC class II restricted antigen restricted pathway. Antibodies are effective on paraffin-embedded sections1. Staining is cytoplasmic with membrane accentuation.

Immunohistochemical expression

Thymocytes, helper/inducer T lymphocytes, monocyte/macrophages, granulocytes and Langerhans' cells. It is not expressed by B cells. Normally, CD4 and CD8 are mutually exclusive.

some T-ALL/T-LBL

Diagnostic utility

Identifies Helper/inducer T lymphocytes. Most peripheral T cell lymphomas are CD4+/CD8-.

gdT-cell lymphomas are usually CD4-/CD8- (less often CD4-/CD8+).

ALCL are more often CD4+ than CD8+.

True histiocytic lymphomas are CD4+.

Blastic NK cell lymphomas are CD4+.

CD4 positivity in cutaneous T-cell lymphomas may be associated with a better prognosis.

In mature T-cell proliferations, either a CD4-/CD8- or a CD4+/CD8+ profile is aberrant and is supportive of a diagnosis of lymphoma.

References

1Leong A S-Y, Cooper K and Leong FJ W-M. Manual of diagnostic antibodies for immunohistology. 2nd edition, 2003