Chondroitin sulfate proteoglycan-4 (CSPG4)-specific monoclonal antibody 225.28 in detection of acute myeloid leukemia blasts.

Chondroitin sulfate proteoglycan-4 (CSPG4), a membrane-bound proteoglycan known to be expressed on the surface of malignant cells, has a restricted distribution in normal tissues. CSPG4 is a potential candidate tumor marker. We investigate CSPG4 expression on blasts in newly diagnosed acute myeloid leukemia (AML) patients and its relation with cytogenetic abnormalities and molecular markers known to have prognostic significance in this disease. Using hybridoma technology, we generated a specific monoclonal antibody (mAb), mAb 225.28, reactive with CSPG4. Blast samples obtained from the peripheral blood of newly diagnosed AML patients were analyzed for CSPG4 expression using the CSPG4-specific mAb and multiparameter flow cytometry. The results were correlated with cytogenetic and molecular characteristics of AML. CSPG4 was found to be expressed on a variable fraction of leukemic blasts in all AML patients with different leukemia morphology, including monoblastic cases. Reactivity of CSPG4-specific mAb with leukemic blasts was not limited to those with the rearranged MLL gene. CSPG4 was also expressed on AML blasts with a complex karyotype, FLT3 mutation, or NPM1 mutation. The results indicate that CSPG4 is expressed and detectable by flow cytometry using the mAb 225.28 on a proportion of blasts of all subtypes of AML irrespective of cytogenetic and molecular abnormalities. mAb 225.28 could be useful in detecting AML blasts by flow cytometry.