57 The more pronounced down-regulation of CD20 in activated rhesus B cells may have implications in experimental settings or evaluation of treatment strategies that use antibodies to CD20 for selective depletion of B cells. The type of adjuvant to be chosen for a certain vaccine depends on the nature of the antigen and the type of immune response required for optimal protection. CpG has been used successfully in clinical trials as an adjuvant to

the Engerix-B hepatitis B virus vaccine and an influenza vaccine.21–23 In addition, CpG successfully increased the response to therapeutic vaccination in HIV-infected patients58 and is therefore of interest as an adjuvant for cancer metabolism inhibitor immune-suppressed individuals.10 The use of ligands targeting TLR7/8 selleck may be promising for situations where mDCs and pDCs as well as B cells would be advantageous to directly activate to enhance immune responses including cross-presentation and/or antibody production. Both TLR7/8-L and CpG C have been shown,

when administered to rhesus macaques together with an HIV Gag protein, to significantly increase Gag-specific T helper type 1 (Th1) and antibody responses.19,20 The adjuvant effect of several TLR-ligands has been shown to be type I IFN dependent. For example complete Freund’s adjuvant and IC31, adjuvants that both include signalling via TLR9, lost their adjuvant effect in mice lacking the IFN-α/β receptor.59,60 Also Poly I:C, when used with a protein-based vaccine in a mouse model, required systemic type I IFN production

for its adjuvant activity. Of note, IFN-α production to Poly I:C was TLR-independent and mediated to a large extent by non-haematopoietic stromal cells.61 Molecular motor Therefore, for future adjuvant development, the contribution of both haematopoietic and non-haematopoietic cells needs to be considered in terms of type I IFN production. Although direct IFN signalling on DCs was shown to be central to induce adjuvant effects,60,61 in certain circumstances, adjuvant effects mediated by type I IFN require direct signalling on B cells and T cells.9 Different pathogens may require different types of immune responses to cause protection and so the adjuvant may be chosen accordingly to shape the desired responses.62 The currently most used adjuvant is alum, which functions mainly by induction of humoral responses. Several new vaccines in development are also likely to require effective Th1 immunity to induce protection. Ligation of TLR3, TLR4, TLR7/8 and TLR9 generally elicits Th1 cell responses.62 Therefore, the respective TLR-ligands are promising for use in adjuvant formulations. Considering the potent enhancing effect of IFN-α in our B-cell cultures upon stimulation with TLR7/8-ligand, a combination of TLR7/8-ligand with Poly I:C, which induces systemic IFN-α levels, may be promising.