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Published on: March 14, 2011
Induction of CD5 antigen on human CD5- B cells by stimulation with Staphylococcus aureus Cowan strain I
K Morikawa1, F Oseko, S Morikawa
1Department of Internal Medicine, Shimane Medical University, Japan.
Insights
Human B cells can acquire the CD5 phenotype when stimulated with Staphylococcus aureus Cowan strain I (SAC). This study demonstrates that CD5- B cells can be induced to express CD5, a key marker in B cell activation and differentiation.
Area of Science:
- Immunology
- Cell Biology
Background:
- The CD5 molecule is a marker expressed on certain human B cell subsets, playing a role in immune regulation.
- The induction of CD5 expression on B cells by external stimuli is not fully understood.
Purpose of the Study:
- To investigate whether the polyclonal B cell stimulator, Staphylococcus aureus Cowan strain I (SAC), can induce CD5 phenotype expression on human B cells.
- To explore the characteristics and cell cycle dynamics of SAC-induced CD5+ B cells.
Main Methods:
- Human tonsillar B cells were isolated using Percoll density gradient centrifugation.
- Cells were cultured in vitro with or without Staphylococcus aureus Cowan strain I (SAC).
- Flow cytometry was used to analyze CD5 expression and other activation markers; cell sorting was performed for further functional analysis.
Main Results:
- Staphylococcus aureus Cowan strain I (SAC) significantly increased the percentage of CD5+ B cells in human tonsillar B cell cultures.
- CD5 expression was observed on various B cell subsets and correlated with cell size enlargement.
- CD5 antigen induction occurred during the G0 to G1 phase transition of the cell cycle, and CD5- B cells could be induced to express CD5 upon SAC stimulation.
Conclusions:
- Human CD5- B cells possess the capacity to express the CD5 phenotype upon stimulation with the polyclonal B cell activator, SAC.
- This finding provides insights into B cell activation pathways and the plasticity of B cell surface marker expression.
Abstract:
We have examined whether the CD5 phenotype could be induced on human B cell surfaces by the polyclonal B cell stimulator, Staphylococcus aureus Cowan strain I (SAC). Fresh tonsillar B cells were prepared by Percoll density gradient from E- cells. The proportion of CD5+ B cells in the 50/60% and 60/70% interface high-density fractions varied between 1.2 and 10.2% depending on the tonsil preparations when they were placed on the in vitro culture 12-60 h prior to flow cytometric analysis. The expression of CD5 antigen obviously increased in the presence of SAC (1:10(5) v/v). The percentage of CD5+ B cells varied from tonsil to tonsil, from 25.1 to 65.9% in a series of experiments. The CD5+ B cells were found both among CD23+CD25+CD71+ and CD23-CD25-CD71- B cells. The level of CD5 expression was related to the cell size enlargement. The addition of anti-CD5 antibody in the culture blocked the CD5 induction by SAC without interfering with the expression of other activation markers. A time-course study showed that CD5 antigen appeared to be induced on the cell surface during the G0 to G1 phase transition in the cell cycle. When CD5+ and CD5- B cells were separated by magnetic isolation, the CD5- B cells showed DNA synthesis to the stimulation by SAC and expressed CD5 antigen on their cell surface. These results suggest that human CD5- B cells can express the CD5 phenotype by stimulation with the polyclonal B cell stimulator, SAC.
