Background & objective: The expression of some antigens has been involved in cytogenetic abnormalities in leukemia. This study was to explore the immunophenotypes of acute myelomonocytic leukemia (M4), analyze the correlation of M4 to cytogenetic abnormalities, and provide evidences for the diagnosis and therapy.
Methods: Immunophenotypic analysis was performed using a panel of monoclonal antibodies and three-color immunofluorescent staining methods of flow cytometry in 81 patients with M4 leukemia. Cytogenetic records of 73 patients were available, among which 35 were further investigated by dual-color interphase fluorescent in situ hybridization (FISH) and the immunophenotype of inv(16)-positive patients were analyzed.
Results: Among the 81 M4 leukemia patients, CD33 (84.0%) was the most commonly expressed antigen, followed by CD13 (81.5%) and CD14 (24.7%). CD34 was detected in 48 (59.3%) patients. T lymphoid-and B lymphoid-associated antigens were expressed in 23 (28.4%) and 10 (12.3%) patients, respectively. All the 11 patients with M4Eo had CD13 expression. CD33, CD34, and CD2 were expressed in 10, 7, and 5 patients, respectively. Of the 14 patients with inv(16), 13 expressed CD13, 11 expressed CD33, 8 expressed CD34, 5 expressed CD14, 3 expressed CD7, and 3 expressed CD2. Of the 73 patients with cytogenetic records, 30 (41.1%) had clonal chromosomal abnormalities. The expression of CD2 and CD34 was associated with karyotypic abnormalities. The expression of CD2 was higher in M4Eo patients, with no correlation to inv(16).
Conclusions: Acute myelomonocytic leukemia mainly expresses myeloid lineage antigens. The expression of CD2 and CD34 is correlated to karyotypic abnormalities. The expression of CD2 is higher in M4Eo. Inv(16) exists in 40% of M4 patients and the expression of all the antigens has no correlation to inv(16).