CD5

(Leu-1)

Recommended positive control: Tonsil, lymphoid tissues

Staining pattern: membrane

Reacitivity in normal cells: T lymphocytes.  A small number of normal B-cells (John KC Chan. Tumors in lymphoretiucular system in Flercher et al. Diagnostic histopathology of tumors p1106)

Diagnostic utilities:

1) Classification of B-cell lymphomas

small lymphocytic lymphoma/leukemia　~80%

mantle cell lymphoma ~95%

Follicular lymphoma and MALT lymphoma are negative.

(Dorfman DM, Shahsafaei A.Usefulness of a new CD5 antibody for the diagnosis of T-cell and B-cell lymphoproliferative disorders in paraffin sections. Mod Pathol. 1997 Sep;10(9):859-63.)

Note:  Alway compare to CD3, because normal T-cells are positive for thist marker.

Figure: Compare the number of positive cells of CD3 and CD5, the latter is much higher, indicating CD3-negative T-cells are showing positivity for CD5. Positive intensity in B-cells is usually lower than that of T-cells.

2) Some diffuse large B-cell lymphoma express CD5 (CD5-positive diffuse large B-cell lymphoma), showing poorer prognosis then negative cases.

3) Diagnosis of thymic carcinoma. Thymic cancer may show positive for CD5 (50%), and thymomas and carinomas oth other sites are negative.

(Dorfman DM, Shahsafaei A, Chan JK. Thymic carcinomas, but not thymomas and carcinomas of other sites, show CD5 immunoreactivity. Am J Surg Pathol. 1997 Aug;21(8):936-40)