SCYM Clinical Applications 2

Question 1

Which flow cytometric assay is the gold standard for diagnosing paroxysmal nocturnal hemoglobinuria (PNH)?

Accepted Answer

CD55/CD59 expression on red blood cells and granulocytes

Answer

PNH is diagnosed by demonstrating GPI-anchor deficiency via loss of CD55 and CD59 on erythrocytes and granulocytes using flow cytometry.

Question 2

In a bone marrow transplant setting, chimerism analysis by flow cytometry is best performed using which approach?

Accepted Answer

HLA-specific antibodies targeting donor vs. recipient alleles

Answer

HLA allele-specific antibodies allow discrimination of donor versus recipient cells for post-transplant chimerism monitoring.

Question 3

A patient with suspected B-cell lymphoma shows CD10+, BCL-6+, CD5-, CD23- immunophenotype. Which diagnosis is most consistent?

Accepted Answer

Follicular lymphoma

Answer

Follicular lymphoma classically expresses CD10 and BCL-6 while lacking CD5 and CD23.

Question 4

Which surface marker combination is most specific for identifying plasma cells by flow cytometry in bone marrow?

Accepted Answer

CD138+/CD38bright/CD19-/CD45dim

Answer

Plasma cells are CD138+, CD38bright, CD19-/dim, and CD45dim/negative, distinguishing them from other B-lineage cells.

Question 5

In HIV monitoring, the CD4:CD8 ratio typically falls below what threshold to indicate significant immunosuppression?

Accepted Answer

1.0

Answer

A CD4:CD8 ratio below 1.0 indicates immune inversion and is associated with significant immunosuppression in HIV disease.

(SCYM) Specialist in Cytometry Practice Test