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)
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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
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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
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4
Q

Mitogens

A
  • plant derived lectins that bind CHO residues on cell surface glycoproteins and cause lymphocytes to divide
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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
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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
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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**
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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

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