B2 HIV testing

Question 1

Describe HIV
what cells are infected
what can be monitored

Answer 1

Infects CD4 Tc & results in a decline In no.
Monitoring no CD4 can follow the progression towards AIDS via flow cytometry.
(monitoring CD4 can also tell effectiveness of chemotherapy)

Question 2

Describe the progression of HIV

Answer 2

Acute infection > Chronic lymphadenopathy > Sub clinical immune disfunction >
Skin & mucous membrane defects > Systemic immune deficiency (AIDS)

Question 3

How can we quantify T Helper cell number in Blood ?

Answer 3

Lymphocytes can be split into diff pops ID by surface markers
Th: CD3/CD4 = double +ve staining
(cyto CD3/CD8)

Question 4

Describe Fluorescent Microscopy

Answer 4

Quantify no. lymphocytes in a known volume of blood
Examine smear/cytospins with fluorescent microscope
can count no. & % of marker cells

Question 5

Problems with Fluorescent Microscopy

Answer 5

Time consuming Can only count a small no. of cells

Dependent on operator interpretation of each cell

Question 6

Describe Flow Cytometer

Answer 6

Analyses cell suspensions
Cells passed through laser beam - Light emitted from each individual cell is collected & analyses using a computer
Forward Scatter: light emitted from cells at narrow angles to the axis of the laser is proportional to cell size
Side Scatter: Light emitted from cells at right angles to axis of laser is proportional to cell granularity and complexity of surface topography