Utility of CD11a and CD18 in the Diagnosis of Acute Promyelocytic Leukemia by Flow Cytometric Immunophenotyping.
Yi Zhou, Jeffrey L Jorgensen, Sa A Wang, L Jeffrey Medeiros, Sergej N Konoplev. University of Texas MD Anderson Cancer Center, Houston
Background: Acute promyelocytic leukemia (APL) is a curable disease, but it can be rapidly fatal if the patient is not diagnosed and treated in a timely fashion. Flow cytometric immunophenotyping (FCI) has a rapid turn around time, and may serve as a screening test for confirmatory molecular/cytogenetic tests for t(15;17)(q22;q21/PML-RARA). CD34-/HLA-DR-/CD117+ is a well recognized phenotype for APL, but is known to lack specificity. The leukocyte integrin αL β2 (CD11a/CD18) is expressed in most cases of acute myeloid leukemia (AML). In a small number of published studies, CD11a/CD18 was often dim or negative in APL. The goal of this study was to examine CD11a/CD18 expression in a group of APL cases and in a group of AML cases in which APL was considered in the differential diagnosis.
Design: We retrospectively examined 83 cases of AML with a clinical, morphologic, or immunophenotypic suspicion for APL, for which CD11a and CD18 were added to our routine AML FCI panel (which also included CD34 and HLA-DR). A marker was scored as positive if 30% or more of the blasts were brighter than isotype controls. All cases of APL were confirmed by molecular/cytogenetic testing.
Results: There were 43 cases of APL and 40 cases of non-APL, which were mostly AML with or without maturation (WHO criteria). The results for CD11a, CD18, CD34 and HLA-DR were as follows. Considering these markers singly, HLA-DR (absence) was the most sensitive for APL, but all single markers had low specificity in this study group. The classic CD34-/HLA-DR- pattern showed moderate sensitivity and specificity for APL. A pattern of negativity for CD11a and/or CD18 showed high sensitivity but lower specificity. Negativity for all four antigens had the highest specificity but lacked sensitivity.
|APL N (%)||Non-APL N (%)||Specificity|
|HLA-DR-||42 (98)||14 (35)||65%|
|CD34-||36 (84)||16 (40)||60%|
|CD18-||38 (88)||20 (50)||50%|
|CD11a- or CD18 -||42 (98)||26 (65)||35%|
|CD34-/DR -||35 (81)||11 (28)||72%|
|CD11a-/CD18 -||33 (77)||10 (25)||75%|
|DR-/CD11a-/CD18-||32 (74)||6 (15)||85%|
|CD34-/DR-/CD11a-/CD18-||27 (63)||4 (10)||90%|