Related Experiment Videos
Peripheral lymphoid hyperplasia and central lymphoid depletion in mice treated with a bacterial B-cell mitogen
M Lima1, D Portnoi, A Bandeira
1Department of Immunology, Institute for Biomedical Sciences Abel Salazar, Porto, Portugal.
Insights
Streptococcus intermedius protein p90 triggers B-cell activation and T-cell responses in mice. This protein also causes lymphoid hyperplasia and depletion in lymphoid organs, affecting B-cell and T-cell development.
Area of Science:
- Immunology
- Microbiology
- Cell Biology
Background:
- Streptococcus intermedius produces a protein known as p90.
- p90 exhibits both mitogenic and immunosuppressive properties.
- The precise mechanisms underlying p90's effects require further investigation.
Purpose of the Study:
- To elucidate the mechanism of p90's mitogenic and immunosuppressive effects.
- To analyze the impact of p90 on peripheral and central lymphoid organs in mice.
- To characterize the cellular responses, particularly B-cell and T-cell activation and development.
Main Methods:
- Flow cytometry was employed to analyze lymphoid organs.
- Peripheral and central lymphoid organs of treated mice were studied.
- B-cell repertoire and T-cell receptor (V beta-TcR) families were analyzed.
Main Results:
- p90 induced significant B-cell blastogenesis in spleen and lymph nodes.
- A polyclonal T-cell activation was observed, affecting both CD5+ and CD5- B cells.
- Peripheral lymphoid hyperplasia and central lymphoid depletion occurred, with notable effects on bone marrow B-cell precursors and thymocyte populations.
Conclusions:
- p90 significantly impacts adaptive immune responses by modulating B-cell and T-cell populations.
- The observed lymphoid hyperplasia and depletion suggest a complex regulatory role for p90 in immune homeostasis.
- Further research is warranted to explore the therapeutic potential of p90 in modulating immune responses.
Abstract:
In order to further understand the mechanism mediating the mitogenic and immunosuppressor effects of p90, a protein produced by Streptococcus intermedius, flow cytometric studies were performed on peripheral and central lymphoid organs of mice treated with this protein. p90 induced a strong blastogenic B-cell response in the spleen and lymph nodes, followed by a slight but significant polyclonal T-cell activation. B-cell repertoire analysis indicated that polyclonal B-cell responses affected similarly both CD5+ and conventional (CD5-) B cells in the spleen. Repertoire analysis of T cells failed to reveal any preferential stimulation of the V beta T-cell receptor (V beta-TcR) families studied. Peripheral lymphoid hyperplasia was observed concomitantly with central lymphoid depletion. In the bone marrow, pre-B and B cells were profoundly depleted, with a more pronounced effect on small pre-B cells. In the thymus, double-positive (CD4+CD8+) thymocytes were preferentially eliminated, with a relative enrichment of single positive (either CD4+ or CD8+) and double-negative (CD4-CD8-) thymocytes.