Listeria cell wall fraction: a B cell adjuvant

Area of Science:

• Immunology
• Microbiology

Background:

• Listeria monocytogenes cell wall fraction (LCWF) previously induced resistance to Listeria infection, acted as a B cell mitogen, and an immunologic adjuvant in mice.
• The mechanisms underlying LCWF's immunomodulatory effects require further elucidation.

Purpose of the Study:

• To investigate the impact of LCWF on T cell-independent B cell populations.
• To determine if LCWF's adjuvant activity is T cell-dependent.

Main Methods:

• Stimulation of murine B cell populations (nude mouse spleen cells, anti-theta serum-treated spleen cells, bone marrow-derived spleen cells) with LCWF.
• Assessment of sheep erythrocytes coated with LCWF as thymus-independent antigens.
• Evaluation of LCWF's effect on T cell education in vivo.

Main Results:

• LCWF stimulated immune responses in B cell populations that are typically unresponsive to thymus-dependent antigens, especially when T cells were depleted.
• LCWF converted sheep erythrocytes into thymus-independent antigens.
• LCWF's adjuvant effect on B cells was not enhanced by T cells, and it did not improve T cell education.

Conclusions:

• LCWF directly stimulates B cells, independent of T cell activity.
• These findings highlight the potential role of B cells in mediating resistance to Listeria monocytogenes infection.