The clinical and diagnostic relevance of CD23 expression in the chronic lymphoproliferative disease.

CD23 antigen is a cell surface protein considered important in the differentiation of chronic lymphocytic leukemia (CLL) from other lymphoid leukemias. To better clarify CD23 role as a diagnostic tool, the authors retrospectively evaluated clinical and laboratory features of 372 patients who were referred to M.D. Anderson Cancer Center with a diagnosis of CLL or B-cell chronic lymphoproliferative disease. Most of the patients (91%) were CD19+/CD5+. Only 6% of these CD19+/CD5+ patients were CD23-. Overall, CD23- patients had the worse prognostic features compared with CD23+ cases, including anemia (P = 0.03), massive splenomegaly (P = 0.000), high lactate dehydrogenase (P = 0.007), high beta2-microglobulin (P = 0.006), older age (P = 0.001), and male gender (P = 0.02). Surface immunoglobulin expression was moderate/strong in 19 (82%) patients, and FMC-7 was positive in 22 (96%) patients. None of the 13 patients tested for CD10 expressed the antigen. Based on morphology, of the CD23, 16 (70%) were diagnosed with mantle cell leukemia (MCL) was diagnosed in 16 (70%) CD23- patients, 3 (13%) with splenic marginal-zone leukemia, 3 (13%) with prolymphocytic leukemia (PLL) or PLL/CLL, and 1 (4%) with CLL. No cyclin D1 protein expression was noted by Western blot analysis in the one case that showed typical CLL morphology, and this patient did not require therapy. On the whole, the survival rate of CD23- patients was significantly worse than that of patients with CD23+. In contrast, 15 of 32 (49%) CD19+/CD5- patients were CD23-. CD23 negativity in this group was not associated with distinct clinical features or outcome. Eleven (73%) of these patients were classified as having splenic marginal-zone lymphoma and 4 as having follicular lymphoma. These data indicate that CD23 negativity is rare in typical B-cell CLL, and CD23 negativity in patients with CD19+/CD5+ is suggestive of mantle cell leukemia a more aggressive disease with poor response to conventional therapy in which newer chemotherapy regimens such as hyper-CVAD may be more effective.