Fig. 4.

iNKT cells can provide cognate and non-cognate T cell help to B cells. a Cognate help is characterized by rapid and transient anti-lipid antibody production, formation of short-lived germinal centers, but no generation of memory cells. b Non-cognate help of iNKT to B cells arises when peptide antigen is admixed with αGalCer (or other iNKT agonist). Antigen-presenting cells are able to simultaneously present peptide antigens on MHC Class II and αGalCer on CD1d. Upon recognizing αGalCer-CD1d complex, activated iNKT cells promote presentation of peptide antigens to T cells. Subsequent interaction between T and B cells proceeds like a typical T-cell-dependent response, resulting in generation of antibodies against peptide antigen. The non-cognate iNKT cell help is independent of CD1d expression on B cells