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Published on: February 7, 2013
[Immunoglobulin production by human peripheral B cells against Staphylococcus aureus]
1Department of Internal Medicine, Teikyo University School of Medicine, Tokyo, Japan.
Insights
Human B cells produce minimal immunoglobulin (Ig) without T cell help. Activated T cells significantly enhance B cell Ig production against Staphylococcus aureus, crucial for local immune defense.
Area of Science:
- Immunology
- Microbiology
Background:
- Investigates B cell immunoglobulin (Ig) production in response to Staphylococcus aureus.
- Examines both thymus-independent (TI) and thymus-dependent (TD) immune responses in vitro.
Purpose of the Study:
- To elucidate the role of T cells and specific cytokines in enhancing B cell Ig production against Staphylococcus aureus.
- To understand the mechanisms of TI and TD immune responses against Staphylococcus aureus.
Main Methods:
- Human peripheral B cells were cultured with formalinized Cowan I strain Staphylococcus aureus (SAC) or anti-CD3 stimulated T cells.
- Immunoglobulin content in supernatants was measured using specific sandwich ELISA after 10 days.
Main Results:
- B cells produced minimal Ig when activated with SAC alone.
- Interleukin-2 (IL-2) or recombinant CD40 ligand plus IL-2 significantly enhanced Ig production by SAC-induced B cells.
- Optimal Ig secretion by B cells occurred with low anti-CD3 T cell stimulation or fewer T cells; high stimulation/numbers were inhibitory.
Conclusions:
- Antigen-non-specific, activated T cells are critical for enhancing TI immune responses against Staphylococcus aureus, supporting local humoral immunity.
- TD antigen-induced Ig secretion against Staphylococcus aureus depends on the T cell/B cell ratio and CD3 stimulation levels.
Abstract:
Immunoglobulin (Ig) production by human B cells in thymus-independent (TI) and -dependent (TD) immune response against Staphylococcus aureus was investigated in vitro. Highly purified human peripheral B cells were cultured either in the presence of formalinized Cowan I strain Staphylococcus aureus (SAC) or with anti-CD3 stimulated T cells, and Ig content in supernatants was analyzed after 10 days of culture by specific sandwich ELISA. When activated with SAC in the absence of T cells, B cells produced minimal amounts of Ig. In the presence of interleukin-2 (IL-2) or supplemental recombinant CD40 ligand plus IL-2, Ig production by SAC-induced B cells was dramatically enhanced. When cultured with T cells stimulated with low concentrations of anti-CD3 or when cultured with smaller numbers of T cells, B cells produced large amounts of Ig, whereas T cells stimulated with higher concentrations of anti-CD3 or large numbers of T cells failed to induce effective Ig secretion by B cells. These findings suggest that TI immune response against Staphylococcus aureus is strongly enhanced in the presence of activated T cells in an antigen non-specific manner, indicating its critical role in the local humoral immune defense. Moreover, it is indicated that the secretion of Ig induced by TD antigens participates in the immune defense against Staphyloccocus aureus dependent on activated T cell/B cell ratio or an impact of CD3 stimulation on T cells.
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