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HLA class-II antigen-mediated induction of a proliferative response to anti-IgM in human B lymphocytes
N Mooney1, D Van Alewyk, C Brick-Ghannan
1Institut Biomédical des Cordeliers, Paris, France.
Insights
Human leukocyte antigen (HLA) class-II signaling in B lymphocytes enhances T-cell-dependent antigen responses. This pathway is crucial for B-cell proliferation and immune activation, independent of specific HLA class-II isotypes.
Area of Science:
- Immunology
- Molecular Biology
- Cell Signaling
Background:
- Human leukocyte antigen (HLA) class-II molecules play a critical role in immune responses.
- Signal transduction pathways initiated by HLA class-II engagement are not fully understood.
- Understanding these pathways is key to deciphering T-cell-dependent antigenic stimulation.
Purpose of the Study:
- To investigate the intracellular signaling events triggered by HLA class-II engagement in human B lymphocytes.
- To explore the interplay between HLA class-II-mediated signaling and B-cell receptor (sIg) signaling.
- To determine if HLA class-II signaling can enhance responses to non-mitogenic stimuli, modeling T-cell-dependent antigen responses.
Main Methods:
- Utilized human resting B lymphocytes and monoclonal anti-HLA class-II antibodies.
- Measured intracellular calcium flux, phosphatidylinositol biphosphate hydrolysis, and protein kinase C activation.
- Investigated the combined effects of anti-HLA class-II and non-mitogenic anti-sIg antibodies.
Main Results:
- Signal transduction via HLA class-II molecules induced increased intracellular calcium flux, phosphatidylinositol biphosphate hydrolysis, and protein kinase C activation.
- Combined stimulation with HLA class-II antibodies and a non-mitogenic anti-sIg antibody resulted in a proliferative B-cell response.
- This enhancement of proliferation was observed irrespective of the specific HLA class-II isotype used.
Conclusions:
- HLA class-II-mediated signaling is a significant component of T-cell-dependent immune responses.
- The signaling initiated by HLA class-II molecules can potentiate B-cell proliferation.
- These findings highlight the importance of HLA class-II pathway in adaptive immunity.
Abstract:
Signal transduction via HLA class-II antigens has been studied using human resting B lymphocytes and monoclonal anti-HLA class-II antibodies. An increased intracellular calcium flux, phosphatidylinositol biphosphate hydrolysis and activation of protein kinase C have all been observed following signal transduction via HLA-class-II molecules. The interaction of HLA-class-II-mediated signalling with sIg-mediated signalling has been studied using a non-mitogenic anti-sIg. This combination provides a model for T-cell-dependent antigenic stimulation. The results demonstrate that stimulation via HLA class-II antigens permits a proliferative response to an otherwise non-mitogenic anti-sIg and that this effect is not restricted to one HLA class-II isotype. These data suggest that HLA-class-II-mediated signalling is important in responses to T-cell-dependent antigens.