CD1d-binding glycolipids exert potent adjuvant effects on T-dependent Ab responses. The mechanisms include cognate interaction between CD1d-expressing B cells and TCR-expressing Type I CD1d-restricted natural killer T cells (NKTs). However, the critical NKT-derived factors that stimulate B cells are poorly understood. We tested the hypothesis that CD1d-driven CD40L expression by NKT cells influences humoral immunity. Bone marrow chimeras with CD40L +/+ or CD40L -/- NKT cells were immunized with Ag plus CD1d ligand before measuring Ab responses. CD40L -/- NKT cells stimulated higher endpoint Ab titers than controls expressing CD40L. In contrast, immunization of CD40L -/- mice revealed that CD40L -/- NKT cells could not provide B cell help when Th cells lacked CD40L. We report that CD40L -/- NKT cells can provide help for Ab production and do so cooperatively with CD40L +/+ Th cells. We suggest that the manner in which NKT cells provide B cell help is distinct from that of Th cells.
- B lymphocyte
- NKT cell
ASJC Scopus subject areas
- Molecular Medicine
- Immunology and Microbiology(all)
- Public Health, Environmental and Occupational Health
- Infectious Diseases