The CD5 test is a diagnostic evaluation used in pathology and hematology to detect the expression of the CD5 protein on immune cells. CD5 is a cell-surface marker naturally present on mature T-lymphocytes and a small subset of B-lymphocytes.
Performed via flow cytometry or immunohistochemistry on blood, bone marrow, or tissue biopsies, the test helps clinicians distinguish and classify specific blood cancers. Abnormal expression of CD5 on B-cells strongly points toward conditions like Chronic Lymphocytic Leukemia (CLL) and Mantle Cell Lymphoma. Ultimately, this test plays a vital role in accurate cancer staging, guiding targeted therapies, and monitoring treatment response.