CD44 and CD27 expression pattern in B cell precursor acute lymphoblastic leukemia and its clinical significance.

The expression of CD44 and CD27 molecules correlates with the differentiation stage of B cell precursors. The present study was designed to investigate the prognostic relevance of CD44 and CD27 molecules in patients with B cell acute lymphoblastic leukemia (ALL). CD27 and CD44 expression was determined in 58 patients by flow cytometry and their relation to established prognostic factors and response to therapy was investigated. Four patterns of expression were found; CD27 single positive (SP) in 20.7 % of patients, CD44SP in 25.8 %, CD27CD44 double positive (DP) in 20.7 %, and CD27CD44 double negative (DN) in 32.8 %. CD27 expression and the CD27SP pattern correlated directly with TEL/AML1 genotype (P = 0.012). Conversely, CD44 expression and the CD44SP pattern correlated inversely with this genotype (P = 0.016). Patients with the DP pattern had a lower WBC count (P = 0.03), lower percentage of blasts in their bone marrow (P = 0.028), and higher platelet count, whereas CD44SP patients had a higher WBC count and higher percentage of bone marrow blasts. Moreover, a negative association between DN pattern and complete remission (CR) rate was detected (P = 0.03). Mean CD27 expression was significantly higher in low-risk group and in patients who achieved CR (P = 0.001), and in those with a higher platelet number (P = 0.046) and less extramedullary involvement (P = 0.008). Although survival and CR duration were longer in patients with DP pattern and shorter in those with DN pattern, the result did not reach statistical significance. The expression of CD27 together with CD44 showed a relationship with several established risk factors as well as response to therapy, indicating the biological significance of these molecules in ALL.