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Enforced and prolonged CD40 ligand expression triggers autoantibody production in vivo
L Santos-Argumedo1, I Alvarez-Maya, H Romero-Ramírez
1Department of Molecular Biomedicine, Centro de Investigación y Estudios Avanzados, México, Mexico. lesantos@mail.cinvestav.mx
Insights
Enforced CD40 ligand expression on B cells triggers autoantibody production by overcoming normal regulatory mechanisms. This model helps study autoimmune responses and CD40-CD154 roles in primary immune responses.
Area of Science:
- Immunology
- Cell Biology
- Autoimmunity
Background:
- CD40 and its ligand CD154 are crucial for B cell development and thymus-dependent humoral immunity.
- CD154 expression is tightly regulated to prevent B cell bystander activation.
- Current methods to study CD40 stimulation include antibodies, T cell membranes, or transfected cells.
Purpose of the Study:
- To evaluate the effects of CD40-CD40 ligand interaction using CD154-transfected L929 cells in vitro and in vivo.
- To investigate how enforced and prolonged CD40 ligand expression impacts B cell activation and autoantibody production.
Main Methods:
- Utilized CD154-transfected L929 cells for in vitro and in vivo B cell stimulation.
- Performed in vitro assays to assess B cell proliferation, molecule up-regulation, and apoptosis rescue.
- Conducted in vivo spleen inoculation experiments in mice to monitor autoantibody production.
Main Results:
- In vitro, CD154-L929 cells induced IL-4-dependent B cell proliferation, up-regulated CD23, CD54, and MHC class II, and rescued WEHI-231 lymphoma cells from apoptosis.
- In vivo, spleen inoculation of CD154-L929 cells led to transient anti-erythrocyte autoantibody production.
- Enforced CD40 ligand expression bypassed normal regulatory mechanisms, leading to autoantibody generation.
Conclusions:
- Enforced and prolonged CD40 ligand expression overrides regulatory mechanisms controlling B cell activation.
- This system provides a model for studying early autoimmune responses and the role of CD40-CD154 in primary in vivo immune induction.
- The findings highlight the potential for dysregulated CD40-CD154 interaction to induce autoimmunity.
Abstract:
CD40, a glycoprotein expressed on B lymphocytes plays an important role in B cell development, growth and differentiation. The ligand for the CD40 is a 39-kDa glycoprotein (CD154) expressed on the surface of activated T lymphocytes and is essential for thymus-dependent humoral immunity. The expression of CD154 is tightly regulated and its transient expression reduces the chances of potentially deleterious bystander activation of B cells. Stimulation through CD40 has been studied in vitro by using antibodies against CD40, by membranes of activated T cells or lately, by CD154 transfected cells. In this work we have evaluated the outcome of CD40-CD40 ligand interaction in vitro and in vivo by using CD154-transfected L929 cells. In vitro assays showed that CD154-L929 cells can induce on B cells: IL-4-dependent proliferation, up-regulation of CD23, CD54 and class II molecules and can also rescue WEHI-231 B cell lymphoma from anti-IgM-induced apoptosis. Interestingly, in vivo assays revealed that when CD154-L929 cells were inoculated into the spleen, mice developed a strong but transient production of anti-erythrocyte autoantibodies. Through B lymphocyte activation with CD154-transfected L929 cells both in vitro and in vivo, our data reveal that enforced and prolonged expression of CD40 ligand overcomes the tightly regulated mechanisms of B cell activation, triggering the production of autoantibodies. This system might be used to evaluate the early steps of an autoimmune response and the role of CD40-CD154 in the induction of primary responses in vivo.