Expression of the CD5 Molecule in Chronic Lymphocytic Leukemia

CD5 is a T cell marker, aberrantly expressed in B cell chronic lymphocytic leukemia (B-CLL) and mantle cell lymphoma (MCL). Other chronic B cell malignancies, including hairy cell leukemia (HCL) and B cell prolymphocytic leukemia (B-PLL), are usually CD5-. In this study, CD5 expression was investigated in leukemia cells from 42 patients with chronic B cell lymphoproliferative disease. Immunophenotyping was accomplished by flow cytometry with a panel of monoclonal antibodies specific to chronic lymphoproliferative disease such as: CD3, CD4, CD5, CD7, CD8, CD10, CD14, CD16/56, CD19, CD22, CD23, HLADR, CD45, anti-immunoglobulin heavy chain (IgH), anti- kappa and lambda light chain. The hematological parameters were obtained using a hematological analyzer and cytomorphology in Leishman-stained blood films. Information about the patients such as age, sex and clinical data related to the disease was collected. Of the 42 patients, 22 were male and 20 female. Immunophenotyping showed that 35 cases were B-CLL, 3 B-PLL and HCL and one MCL. The lymphadenopathy and splenomegaly were present in 73.8% and 71.4% of cases, respectively. CD5 expression was present in all B-CLL and MCL cases. However, in HCL, and B-PLL, CD5 expression was negative in all cases. In conclusion, these data demonstrated that CD5 expression is useful in distinguishing B-CLL from other chronic B cell malignancies such as HCL and B-PLL, but not between B-CLL and MCL, where positivity may be present in both.