NKT-cell help to B lymphocytes can occur independently of cognate interaction

Elena Tonti, Grazia Galli, Carmine Malzone, Sergio Abrignani, Giulia Casorati, Paolo Dellabona

Research output: Contribution to journalArticlepeer-review


CD4 + T (Th)-cell help to B lymphocytes requires cognate interaction and CD40 engagement. Invariant natural killer T (iNKT) cells are innate-like T lymphocytes that recognize αgalactosylceramide (αGalCer) presented by CD1d, and can help B-cell responses. We asked whether ivGalCer-activated iNKT cells help B lymphocytes through cognate interaction, or indirectly, via enhancement of Th-B-cell interaction. After immunization with protein Ags and vGalCer, antibody titers were assessed in wild-type or splenectomized mice, and in bone marrow radiation chimeras lacking CD1d or CD40 expression on B lymphocytes, or expressing CD1d or MHC II disjointly on antigen-presenting cells (APCs). We find that αGalCer- dependent enhancement of B-cell response (1) can occur when B cells do not express CD1d but express CD40; (2) requires that iNKT and Th cells interact with the same APCs that coexpress both CD1d and MHC-II; and (3) takes place without spleen. These findings demonstrate αGalCer-induced help for antibody responses can occur without cognate iNKT/B-cell interaction, and suggest this help entails activation of APCs by iNKT cells, which in turn activate Th cells and their helper functions for B cells. Thus, the αGalCer-induced help recapitulates the function of classical adjuvants that stimulate the innate immune system to support adaptive immune responses.

Original languageEnglish
Pages (from-to)370-376
Number of pages7
Issue number2
Publication statusPublished - Jan 8 2009

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Immunology
  • Hematology


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