Cross-priming allows dendritic cells (DCs) to induce cytotoxic T cell (CTL) responses to extracellular antigens. DCs require cognate 'licensing' for cross-priming, classically by helper T cells. Here we demonstrate an alternative mechanism for cognate licensing by natural killer T (NKT) cells recognizing microbial or synthetic glycolipid antigens. Such licensing caused cross-priming CD8alpha(+) DCs to produce the chemokine CCL17, which attracted naive CTLs expressing the chemokine receptor CCR4. In contrast, DCs licensed by helper T cells recruited CTLs using CCR5 ligands. Thus, depending on the type of antigen they encounter, DCs can be licensed for cross-priming by NKT cells or helper T cells and use at least two independent chemokine pathways to attract naive CTLs. Because these chemokines acted synergistically, this can potentially be exploited to improve vaccinations.

The use of peptidomimetics has emerged as a powerful means for overcoming the limitations inherent in the physical characteristics of peptides thus improving their therapeutic potential. A peptidomimetic approach that has emerged in recent years with significant potential, is the use of beta-amino acids. Beta-amino acids are similar to alpha-amino acids in that they contain an amino terminus and a carboxyl terminus. However, in beta-amino acids two carbon atoms separate these functional termini. beta-amino acids, with a specific side chain, can exist as the R or S isomers at either the alpha (C2) carbon or the beta (C3) carbon. This results in a total of 4 possible diastereoisomers for any given side chain. The flexibility to generate a vast range of stereo- and regioisomers, together with the possibility of disubstitution, significantly expands the structural diversity of beta-amino acids thereby providing enormous scope for molecular design. The incorporation of beta-amino acids has been successful in creating peptidomimetics that not only have potent biological activity, but are also resistant to proteolysis. This article reviews the rapidly expanding applications of beta-amino acids in the design of bioactive peptide analogues ranging from receptor agonists and antagonists, MHC-binding peptides, antimicrobial peptides and peptidase inhibitors. Given their structural diversity taken together with the ease of synthesis and incorporation into peptide sequences using standard solid-phase peptide synthesis techniques, beta-amino acids have the potential to form a new platform technology for peptidomimetic design and synthesis.

From little things big things grow: 14‐Helical N‐acetyl β3‐peptides spontaneously self‐assemble in a unique head‐to‐tail fashion to form fibers from solution. The fiber size can be controlled from the nano‐ to the macroscale. The inherent flexibility in design and ease of synthesis provide powerful new avenues for the development of novel bio‐ and nanomaterials by supramolecular self‐assembly.

Hybrid peptides consisting of alpha-amino acids with judiciously placed beta-amino acids show great promise as peptidomimetics in an increasing range of therapeutic applications. This reflects a combination of increased stability, high specificity and relative ease of synthesis.