Vaccination with activated B cells pulsed with tumor-lysates can induce tumor-specific CD4+ T cells in vivo

Neoepitopes as cancer immunotherapy targets: key challenges and opportunities

Over the last half century, it has become well established that cancers can elicit a host immune response that can target them with high specificity. Only within the last decade, with the advances in high-throughput gene sequencing and bioinformatics approaches, are we now on the forefront of harnessing the host's immune system to treat cancer. Recently, some strides have been taken toward understanding effective tumor-specific MHC I restricted epitopes or neoepitopes. However, many fundamental questions still remain to be addressed before this therapy can live up to its full clinical potential. In this review, we discuss the major hurdles that lie ahead and the work being done to address them.

Utilization of a lentiviral system for the generation of B cells with regulatory properties

B cells are classically considered for their unique capacity to produce antibodies. Besides this, B cells can also present antigen, costimulate T cells, and secrete cytokines. Recent studies have demonstrated that activated B cells could regulate immunity by the secretion of anti-inflammatory cytokines. Because of their capacity to inhibit immune responses, B cells became of interest as a potential vehicle for the treatment of autoimmune disorders via cell-based therapy. Different approaches have been developed to empower B cells with regulatory properties. An attractive strategy involves their genetic engineering to enforce their expression of suppressive genes. This can be achieved using retroviral vectors. However, most retroviral vectors require prior activation of the B cells for transduction, and the administration of activated B cells may lead to unpredictable outcomes in recipients, including to an enhancement of immune responses. In contrast, resting B cells are poorly immunogenic and therefore safer for the suppression of undesired immune responses in adoptive cell therapy. In this chapter, we describe an approach to generate genetically modified resting B cells with lentiviral vectors using a protocol that is rapid, simple, and neither requires nor induces activation of B cells.

Reprogrammed quiescent B cells provide an effective cellular therapy against chronic experimental autoimmune encephalomyelitis

Activated B cells can regulate immunity and have been envisaged as a potential cell-based therapy for treating autoimmune diseases. However, activated human B cells can also propagate immune responses, and the effects resulting from their infusion into patients cannot be predicted. This led us to consider resting B cells, which in contrast are poorly immunogenic, as an alternative cellular platform for the suppression of unwanted immunity. Here, we report that resting B cells can be directly engineered with lentiviral vectors to express antigens in a remarkably simple, rapid, and effective way. Notably, this neither required nor induced activation of the B cells. With this approach we were able to produce reprogrammed resting B cells that inhibited antigen-specific CD4(+) T cells, CD8(+) T cells, and B cells upon adoptive transfer in mice. Furthermore, resting B cells engineered to ectopically express myelin oligodendrocyte glycoprotein antigen protected recipient mice from severe disability and demyelination in EAE, and even induced complete remission from disease in mice lacking functional natural Tregs, which otherwise developed chronic paralysis. In conclusion, our study introduces reprogrammed quiescent B cells as a novel tool for suppressing undesirable immunity.

Generation of RAGE-1 and MAGE-9 peptide-specific cytotoxic T-lymphocyte lines for transfer in patients with renal cell carcinoma

Renal cell carcinomas (RCCs) are supposed to be immunogenic, and several clinical trials of immunotherapy using tumor lysate-pulsed dendritic cells (DCs) have been performed. We report on the generation of RAGE-1 and MAGE-9 peptide-specific CTL lines. RAGE-1 and MAGE-9 are expressed in 56% and 38% of RCCs. Seven MAGE-9- and 13 RAGE-1-derived peptides were found to be immunogenic in the context of the HLA-A*0201 MHC. CTLs were generated by coculture with peptide-pulsed, activated B cells, which were easily generated in great quantities and displayed functional activity for a prolonged period of time. MAGE-9 and RAGE-1 peptide-specific CTL lines were strictly peptide-specific and displayed high cytotoxic activity not only against peptide-loaded T2 cells but also against HLA-A*0201-positive RCC lines, which naturally express MAGE-9, RAGE-1 or both. Thus, B cells are well suited as APCs for the generation of large numbers of tumor peptide-specific CTLs for adoptive transfer. MAGE-9 as well as RAGE-1 may well provide suitable targets for immunotherapy of RCC.