Immunophenotyping is a technique that helps distinguish between different types of leukemia. For this reason, it can be used to determine whether your child has acute lymphoblastic leukemia (ALL) or acute myeloid leukemia (AML). It also distinguishes between each leukemia subtype.
Bone marrow cells express certain proteins on their surface, called antigens. Different cells have different antigens. For this reason, the antigens on the surface of leukemic cells in ALL and AML are different. Immunophenotyping detects these antigens and determines, for example, whether the cancer is affecting a lymphoid or myeloid cell.
How is immunophenotyping done?
To find your child's leukemia subtype, leukemic cells from your child's bone marrow sample are labelled with different fluorescent markers. For example, the lab specialist may use a green marker that can only bind to antigens on lymphoid cells and a red marker that can only bind to antigens on myeloid cells. In this case:
- if your child has ALL, the leukemic cells are lymphoblasts. They will be labelled green.
- if your child has AML, the leukemic cells are myeloblasts. They will be labelled red.
The labelled cells are then run through a special flowing liquid, which has a laser that passes through it. The laser detects the type of fluorescent marker on the leukemic cells.
Sometimes, immunophenotyping can be done on a peripheral blood sample — especially when the white blood count is very high. However, bone marrow immunophenotyping is generally more reliable.