LST Proliferation Assays 2

Question 1

In CFSE dilution assays analyzed by flow cytometry, each successive generation of dividing lymphocytes is characterized by:

Accepted Answer

Fluorescence intensity halved relative to the previous generation

Answer

Fluorescence intensity doubled relative to the previous generation

Answer

No change in fluorescence but increased cell size

Answer

Increased forward scatter with constant fluorescence

Question 2

The Proliferation Index (PI) in a CFSE assay differs from the Division Index in that PI measures:

Accepted Answer

The average number of divisions undergone by cells that actually divided

Answer

The fraction of total cells that entered at least one division

Answer

The total number of cells produced from the original population

Answer

The percentage of cells remaining undivided

Question 3

Which cell density is generally optimal for seeding peripheral blood mononuclear cells (PBMCs) in a standard 96-well proliferation assay?

Accepted Answer

1–2 × 10⁵ cells per well

Answer

1–2 × 10³ cells per well

Answer

1–2 × 10⁷ cells per well

Answer

5 × 10⁴ cells per well in 10 mL medium

Question 4

In a tritiated thymidine proliferation assay, cells are typically harvested onto glass fiber filters using a:

Accepted Answer

Semi-automated cell harvester

Answer

Centrifuge and pipette aspiration

Answer

Magnetic bead separation system

Answer

Density gradient centrifugation

Question 5

EdU (5-ethynyl-2'-deoxyuridine) offers a technical advantage over BrdU for proliferation assays primarily because:

Accepted Answer

EdU detection does not require harsh DNA denaturation steps that damage cell surface antigens

Answer

EdU emits fluorescence without requiring antibody staining

Answer

EdU is incorporated into RNA rather than DNA

Answer

EdU detection can be performed without fixation

Question 6

In an LST proliferation assay, what does a high background CPM in the unstimulated negative control most likely indicate?

Accepted Answer

Spontaneous proliferation due to activated cells, contamination, or excessive cell death triggering bystander activation

Answer

Optimal assay conditions with well-functioning lymphocytes

Answer

Adequate mitogen stimulation of the control well

Answer

Correct thymidine pulse timing

Question 7

The WST-1 colorimetric assay measures lymphocyte proliferation indirectly by detecting:

Accepted Answer

Mitochondrial dehydrogenase activity as a surrogate for viable, metabolically active cells

Answer

Direct DNA synthesis via nucleoside incorporation

Answer

Cytokine release into the culture supernatant

Answer

Cell surface expression of proliferation markers like Ki-67