Diagnostic tests- looking for cell-mediated immunity Flashcards
1
Q
What are some measurable characteristics of T cell responses?
A
- activation marker expression
- proliferation responses (clonal expansion)
- cytokine secretion
- cytotoxicity to target cells (CD8)
2
Q
Activation marker expression: Flow Cytometry
A
- characterizes individual cells
- pass cells through laser, detect and count them
- cells of interest will be fluorescently labelled and excited by laser
- sorted into specific tubes
- put into plots
3
Q
Proliferation responses: clonal expansion
A
- Antigen presented to T cells via MHC, needs 3 signals
- T cells proliferate and clonally expand
- Maturing T and B cells= immunoblasts
- culture with radioactive component (thymidine) and measure uptake = Count number of proliferating cells
4
Q
Mitogens
A
- plant derived lectins that bind CHO residues on cell surface glycoproteins and cause lymphocytes to divide
5
Q
Advances in proliferation measurements
A
radioactivity now replaced with CFSE fluorescent compound. CFSE brightness can be measured with flow cytometry
- huge peak= 0 proliferating cells
- smaller peaks= proliferating cells
6
Q
Cytokine secretion measurement
A
- Use ELISA based assays for cytokines. Culture with mitogens or cytokines
- ELISpot assay- shows IFN-gamma release response of peripheral blood mononuclear cells to a target antigen
7
Q
Cytotoxicity to target cells detection
A
Cytotoxicity assays: measure the T cell mediated killing of a target cell population
Antigen-specific and MHC I restricted
- combine radio labeled target cells and the effector T cell population (must have same MHCI so same patient)
- culture two cell populations together
- if antigen is presented on target cell, T cell will destroy and a release of radioactivity will occur
** measure amount of radioactivity released to find out T cell cytotoxicity**
8
Q
Measure Cell mediated immunity in living
A
Delayed type hypersensitivity Testing (DTH)
- antigen injected into tissues
- Th1 cell recognizes, releases cytokines
- recruitment of phagocytes occurs
- LESION occurs
“TB testing”- response indicates that exposure has occurred before because memory T cell response