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T-cell modulation of the antibody response to bacterial polysaccharide antigens
1Department of Microbiology and Immunology, Medical College of Pennsylvania, Philadelphia 19129.
Abstract:
Pretreatment of mice with subimmunogenic doses of meningococcal polysaccharide (MP), Pseudomonas aeruginosa lipopolysaccharide (PA), or Streptococcus mutans polysaccharide (SM) resulted in suppression of antibody response. The transfer of putative suppressor T cells (Ts cells) from donor mice primed with a subimmunogenic dose of MP to naive recipients at the time of immunization with MP substantially reduced the magnitude of the antibody response. Also, the infusion of B cells taken from animals immunized with either MP or PA suppressed the antibody response of naive recipients to MP or PA, respectively, relative to controls, suggesting that Ts cells respond to determinants on immune B cells. We observed that the injection of concanavalin A or phytohemagglutinin (two lectins known to augment the activity of amplifier T cells [Ta cells]) 2 days postimmunization enhanced the antibody response to MP and SM. In addition, Ta-cell activity was transferred to naive animals by using spleen cells. Although the administration of phytohemagglutinin at the time of immunization with MP also resulted in increased antibody response, the injection of concanavalin A simultaneous with immunization resulted in a suppression of the antibody response to MP. Although Ts cells generated in response to pneumococcal polysaccharide type III were found to respond to monoclonal antibody Ly-m22, Ta cells responded to monoclonal antibodies L3T4 and Ia but not to Ly-m22. These studies suggest that Ta and Ts cells can modulate the antibody response to MP, SM, and PA in a positive and negative manner, respectively.
Insights
Subimmunogenic doses of polysaccharides can suppress antibody responses. Suppressor T cells (Ts cells) and amplifier T cells (Ta cells) modulate immune responses to meningococcal polysaccharide (MP), Pseudomonas aeruginosa lipopolysaccharide (PA), and Streptococcus mutans polysaccharide (SM).
Area of Science:
- Immunology
- Cellular immunology
- Immunomodulation
Background:
- Subimmunogenic doses of certain polysaccharides can suppress antibody production.
- T cells play a crucial role in regulating immune responses.
Purpose of the Study:
- To investigate the role of suppressor T cells (Ts cells) and amplifier T cells (Ta cells) in modulating antibody responses.
- To determine the mechanisms by which Ts and Ta cells influence immune responses to specific polysaccharides.
Main Methods:
- Mice were pretreated with subimmunogenic doses of meningococcal polysaccharide (MP), Pseudomonas aeruginosa lipopolysaccharide (PA), or Streptococcus mutans polysaccharide (SM).
- Transfer of Ts cells and B cells from immunized mice to naive recipients.
- Administration of concanavalin A or phytohemagglutinin to modulate Ta cell activity.
- Use of monoclonal antibodies (Ly-m22, L3T4, Ia) to characterize Ts and Ta cells.
Main Results:
- Pretreatment with subimmunogenic doses of MP, PA, or SM suppressed antibody responses.
- Transfer of Ts cells suppressed antibody response to MP.
- Infusion of B cells from immunized animals also suppressed antibody responses.
- Administration of concanavalin A or phytohemagglutinin enhanced antibody responses to MP and SM, indicating Ta cell activity.
- Ts cells responded to Ly-m22, while Ta cells responded to L3T4 and Ia.
Conclusions:
- Ts and Ta cells can differentially modulate antibody responses to MP, PA, and SM.
- Ts cells mediate suppression, while Ta cells mediate enhancement of antibody production.
- These findings highlight the complex regulatory network governing immune responses to bacterial polysaccharides.