Ligation of CD40 induces maturation of dendritic cells (DC) and could be a useful target for vaccines. In this study, we have constructed two types of Ab-based vaccine constructs that target mouse CD40. One type is a recombinant Ab with V regions specific for CD40 and has defined T cell epitopes inserted into its C region. The other type is a homodimer, each chain of which is composed of a targeting unit (single-chain fragment variable targeting CD40), a dimerization motif, and an antigenic unit. Such proteins bound CD40, stimulated maturation of DC, and enhanced primary and memory T cell responses. When delivered i.m. as naked DNA followed by electroporation, the vaccines induced T cell responses against MHC class II-restricted epitopes, Ab responses, and protection in two tumor models (myeloma and lymphoma). Two factors apparently contributed to these results: 1) agonistic ligation of CD40 and induction of DC maturation, and 2) delivery of Ag to APC and presentation on MHC class II molecules. These results highlight the importance of agonistic targeting of Ag to CD40 for induction of long-lasting and protective immune responses.

Initiation of the adaptive immune response is dependent on the priming of naive T cells by

Initiation of the adaptive immune response is dependent on the priming of naive T cells by

An ideal vaccine for induction of CD4+ T cell responses should induce local inflammation, maturation of APC, and peptide loading of MHC class II molecules. Ligation of Toll-like receptor (TLR) 2 provides the first two of these three criteria. We have studied whether targeting of TLR2 results in loading of MHC class II molecules and enhancement of CD4+ T cell responses. To dissociate MHC class II presentation from APC maturation, we have used an antagonistic, mouse anti-human TLR2 mAb (TL2.1) as ligand and measured proliferation of a mouse Cκ-specific human CD4+ T cell clone. TL2.1 mAb was 100-1000 times more efficiently presented by APC compared with isotype-matched control mAb. Moreover, TL2.1 mAb was internalized into endosomes and processed by the conventional MHC class II pathway. This novel function of TLR2 represents a link between innate and adaptive immunity and indicates that TLR2 could be a promising target for vaccines.

The manufacture of clinical grade cellular products for adoptive immunotherapy requires ex vivo culture and expansion of human T cells. One of the key components in manufacturing of T cell therapies is human serum (HS) or fetal bovine serum (FBS), which can potentially expose immunotherapy recipient to adventitious infectious pathogens and are thus considered as non-cGMP compliant for adoptive therapy. Here we describe a novel xeno-free serum replacement (SR) with defined components that can be reproducibly used for the production of clinical grade T-cell therapies in combination with several different cell culture media. Dynabeads CD3/CD28 Cell Therapy System (CTS)-activated or antigen-specific T cells expanded using the xeno-free SR, CTS Immune Cell SR, showed comparable growth kinetics observed with cell culture media supplemented with HS or FBS. Importantly the xeno-free SR supplemented medium supported the optimal expansion of T cells specific for subdominant tumour-associated antigens and promoted expansion of T cells with central memory T-cell phenotype, which is favourable for in vivo survival and persistence following adoptive transfer. Furthermore, T cells expanded using xeno-free SR medium were highly amenable to lentivirus-mediated gene transduction for potential application for gene-modified T cells. Taken together, the CTS Immune Cell SR provides a novel platform strategy for the manufacture of clinical grade adoptive cellular therapies.