Immunophenotyping is used to identify antigens, or markers, expressed on the outside of the cell. It is utilized to identify lineage assignment, blast enumeration, and leukemia-associated immunophenotypes (LAIP).1,2

Techniques used for immunophenotyping are flow cytometry and immunohistochemistry.2

Flow Cytometry

Flow cytometric immunophenotyping evaluates individual blood or bone marrow cells in suspension for the presence and absence of specific antigens (phenotype). This method can determine whether the cells present are mature or immature and can evaluate lineage in order to differentiate between acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML).3 Combined expression of cell-surface and cytoplasmic markers differentiates various subtypes of AML.4

Throughout the disease trajectory, flow cytometry may be useful for monitoring response to treatment and documenting relapse or progression.2

For more than a decade, flow cytometric immunophenotyping has been an indispensable diagnostic tool. Improvements in flow cytometry instrumentation and availability of additional antibodies and fluorochromes have led to enhanced identification of abnormal cell populations.3

Immunohistochemistry (IHC)

IHC utilizes antibodies to detect specific antigens, which are expressed by certain cancer cells. This is considered an advantage compared to older techniques that were only able to identify a limited number of proteins, enzymes, and tissue structures.5

References: 1. Roug AS, Hansen MC, Nederby L, Hokland P. Diagnosing and following adult patients with acute myeloid leukaemia in the genomic age. Br J Haematol. 2014;167(2):162-176. 2. Tests for Acute Myeloid Leukemia (AML). American Cancer Society website. Updated August 21, 2018. Accessed April 22, 2021. 3. Craig FE, Foon KA. Flow cytometric immunophenotyping for hematologic neoplasms. Blood. 2008;111(8):3941-3967. 4. Döhner H, Estey E, Grimwade D, et al. Diagnosis and management of AML in adults: 2017 ELN recommendations from an international expert panel. Blood. 2017;129(4):424-447. 5. Duraiyan J, Govindarajan R, Kaliyappan K, Palanisamy M. Applications of immunohistochemistry. J Pharm Bioallied Sci. 2012;4(Suppl 2):S307-S309.