Immunophenotypic Markers in Acute Lymphoblastic Leukemia

B-Cell ALL Immunophenotype

The National Comprehensive Cancer Network (NCCN) guidelines identify CD19, along with CD22 and CD79a, as the defining B-cell markers used to establish B-lineage ALL diagnosis, which represents approximately 75-80% of ALL cases 1, 2, 3
CD19 is the hallmark marker for B-cell lineage ALL, expressed consistently across all developmental stages from pro-B-cell through mature B-cell ALL 1, 4, 5

Pro-B-cell (Pre-pre-B) ALL is characterized by CD19+/CD22+/CD79a+, TdT+, CD10 negative 1, 4, 3
Common B-cell ALL is characterized by CD19+/CD10+ (the "common ALL antigen") 1, 3, 5
Pre-B-cell ALL is characterized by CD19+/CD10+/CD22+/CD79a+ with cytoplasmic immunoglobulins 1, 3
Mature B-cell ALL is characterized by CD19+ with surface immunoglobulins, TdT negative 1, 5

B-cell lineage determination through CD19 expression is critical because it directs treatment toward ALL-specific regimens requiring 2-3 years of multi-agent chemotherapy with CNS prophylaxis, which differs completely from AML treatment approaches 8
The presence of aberrant myeloid antigen expression (CD13, CD33) occurs in 25-45% of precursor B-cell ALL cases and is even higher (70.8%) in Philadelphia chromosome-positive ALL, but does not exclude the diagnosis of ALL 1, 4, 5