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Effects of CD40 ligation on human keratinocyte accessory function
J Grousson1, M Concha, D Schmitt
1INSERM U346, Pavillion R, Hôpital Edouard-Herriot, Lyon, France.
Archives of Dermatological Research
|August 15, 1998
Summary
CD40 ligand interactions on keratinocytes amplify inflammation but do not activate T cells. This study reveals CD40 ligation on nonprofessional antigen-presenting cells enhances immune responses without direct T-cell costimulation.
Area of Science:
- Immunology
- Cell Biology
- Dermatology
Background:
- CD40/CD40 ligand interactions are crucial for immune responses, primarily by enhancing professional antigen-presenting cells (APCs).
- The role of CD40 signaling in nonprofessional APCs, such as keratinocytes induced during inflammation, remains largely unexplored.
- Understanding CD40's function on keratinocytes is vital for comprehending inflammatory processes in the skin.
Purpose of the Study:
- To investigate the impact of CD40 ligation on the phenotype and accessory function of human keratinocytes.
- To determine if CD40 signaling on keratinocytes can induce T-cell activation or modulate existing T-cell responses.
- To elucidate the contribution of CD40-CD40 ligand interactions in nonprofessional APCs to immune regulation.
Main Methods:
- Utilized CD40 ligand-transfected cells to stimulate CD40 on human keratinocytes.
- Analyzed changes in keratinocyte phenotype, including ICAM-1, HLA-DR, CD80, and CD86 expression, with and without IFN-gamma treatment.
- Assessed the accessory function of keratinocytes in T-cell activation assays using PHA and superantigens, with and without anti-CD28 or anti-CD40 blocking antibodies.
Main Results:
- CD40 ligation enhanced ICAM-1 expression on IFN-gamma-treated keratinocytes but did not upregulate HLA-DR, CD80, or CD86.
- CD40 triggering alone or with anti-CD28 mAb was insufficient to induce primary allogeneic T-cell responses.
- Keratinocyte accessory function in PHA- or superantigen-induced T-cell activation remained unaltered by CD40 ligation, confirmed by blocking experiments.
Conclusions:
- CD40-CD40 ligand interactions on keratinocytes, a type of nonprofessional APC, can amplify inflammatory reactions.
- These interactions do not provide a sufficient costimulatory or mitogenic signal for T-cell activation.
- CD40 signaling in nonprofessional APCs may contribute to immune amplification without directly driving T-cell proliferation.