SCYM Immunophenotyping 2

Question 1

Which CD marker is characteristically expressed on plasma cells and used to distinguish them from mature B cells in flow cytometry?

Accepted Answer

CD38

Answer

CD38 is highly expressed on plasma cells, whereas mature B cells typically downregulate CD38 and retain CD19/CD20.

Question 2

In immunophenotyping of T-cell lymphomas, loss of which antigen is most commonly used as evidence of aberrant T-cell populations?

Accepted Answer

CD7

Answer

CD7 is the most frequently lost pan-T-cell antigen in T-cell lymphomas, making its absence a useful aberrancy marker.

Question 3

Which combination of markers best identifies natural killer (NK) cells by flow cytometry?

Accepted Answer

CD3-/CD16+/CD56+

Answer

NK cells are CD3-negative but express CD16 and CD56, distinguishing them from NKT cells which are CD3-positive.

Question 4

TdT expression in flow cytometry is most useful for identifying which cell population?

Accepted Answer

Lymphoblasts

Answer

Terminal deoxynucleotidyl transferase (TdT) is a nuclear enzyme expressed in immature lymphoid precursors (lymphoblasts) and is a key marker for ALL.

Question 5

In a patient with suspected chronic lymphocytic leukemia (CLL), which immunophenotypic feature would argue AGAINST a CLL diagnosis?

Accepted Answer

Bright surface immunoglobulin expression

Answer

CLL cells characteristically show dim surface immunoglobulin; bright sIg expression is atypical and suggests mantle cell lymphoma or other B-cell disorders.

(SCYM) Specialist in Cytometry Practice Test

(SCYM) Specialist in Cytometry Practice Test

SCYM Immunophenotyping 2