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Effect of CD4 engagement on CD4-T cell receptor complexes
R S Chuck1, C R Cantor, D B Tse
1Department of Medicine, North Shore University Hospital, Cornell University Medical College, Manhasset, New York 11030.
Cellular Immunology
|November 1, 1993
Summary
Researchers investigated CD4-T cell receptor (TCR) complexes using flow cytometry. Different CD4 engagement methods altered CD4-TCR expression and association, impacting T cell responses.
Area of Science:
- Immunology
- Cell Biology
- Biophysics
Background:
- The CD4-T cell receptor (TCR) complex plays a crucial role in adaptive immunity.
- Understanding the dynamics of CD4-TCR interactions is vital for deciphering T cell activation and regulation.
Purpose of the Study:
- To investigate the changes in CD4, TCR, and CD4-TCR complex expression and association upon CD4 engagement.
- To elucidate the mechanisms by which CD4 ligation affects TCR-mediated signaling.
Main Methods:
- Utilized a previously established flow cytometry method measuring singlet-singlet energy transfer.
- Analyzed human T cells labeled with fluorescein isothiocyanate-conjugated anti-CD4 and tetramethylrhodamine isothiocyanate-conjugated anti-TCR.
Main Results:
- Ligation of the CD4 D3 domain with OKT4 or the D1 domain with anti-Leu3a induced CD4 and TCR down-regulation.
- OKT4 and anti-Leu3a differentially affected CD4-TCR association kinetics at 37°C.
- gp120 ligation affected CD4-TCR association primarily at 0°C, unlike T cell receptor-specific antibodies.
Conclusions:
- Alterations in CD4-TCR complex assembly following CD4 engagement can influence T cell antigen recognition.
- These modifications may explain the inhibitory effects of anti-Leu3a and gp120 on T cell responses.