Functional capacities of human IgM memory B cells in early inflammatory responses and secondary germinal center reactions.

The generation and functions of human peripheral blood (PB) IgM(+)IgD(+)CD27(+) B lymphocytes with somatically mutated IgV genes are controversially discussed. We determined their differential gene expression to naive B cells and to IgM-only and IgG(+) memory B cells. This analysis revealed a high similarity of IgM(+)(IgD(+))CD27(+) and IgG(+) memory B cells but also pointed at distinct functional capacities of both subsets. In vitro analyses revealed a tendency of activated IgM(+)IgD(+)CD27(+) B cells to migrate to B-cell follicles and undergo germinal center (GC) B-cell differentiation, whereas activated IgG(+) memory B cells preferentially showed a plasma cell (PC) fate. This observation was supported by reverse regulation of B-cell lymphoma 6 and PR domain containing 1 and differential BTB and CNC homology 1, basic leucine zipper transcription factor 2 expression. Moreover, IgM(+)IgD(+)CD27(+) B lymphocytes preferentially responded to neutrophil-derived cytokines. Costimulation with catecholamines, carcinoembryonic antigen cell adhesion molecule 8 (CEACAM8), and IFN-γ caused differentiation of IgM(+)IgD(+)CD27(+) B cells into PCs, induced class switching to IgG2, and was reproducible in cocultures with neutrophils. In conclusion, this study substantiates memory B-cell characteristics of human IgM(+)IgD(+)CD27(+) B cells in that they share typical memory B-cell transcription patterns with IgG(+) post-GC B cells and show a faster and more vigorous restimulation potential, a hallmark of immune memory. Moreover, this work reveals a functional plasticity of human IgM memory B cells by showing their propensity to undergo secondary GC reactions upon reactivation, but also by their special role in early inflammation via interaction with immunomodulatory neutrophils.

Titratable Pharmacological Regulation of CAR T Cells Using Zinc Finger-Based Transcription Factors.

Chimeric antigen receptor (CAR) T cell therapy has emerged as an attractive strategy for cancer immunotherapy. Despite remarkable success for hematological malignancies, excessive activity and poor control of CAR T cells can result in severe adverse events requiring control strategies to improve safety. This work illustrates the feasibility of a zinc finger-based inducible switch system for transcriptional regulation of an anti-CD20 CAR in primary T cells providing small molecule-inducible control over therapeutic functions. We demonstrate time- and dose-dependent induction of anti-CD20 CAR expression and function with metabolites of the clinically-approved drug tamoxifen, and the absence of background CAR activity in the non-induced state. Inducible CAR T cells executed fine-tuned cytolytic activity against target cells both in vitro and in vivo, whereas CAR-related functions were lost upon drug discontinuation. This zinc finger-based transcriptional control system can be extended to other therapeutically important CARs, thus paving the way for safer cellular therapies.

Novel adapter CAR-T cell technology for precisely controllable multiplex cancer targeting.

Chimeric antigen receptor (CAR)-T therapy holds great promise to sustainably improve cancer treatment. However, currently, a broad applicability of CAR-T cell therapies is hampered by limited CAR-T cell versatility and tractability and the lack of exclusive target antigens to discriminate cancerous from healthy tissues. To achieve temporal and qualitative control on CAR-T function, we engineered the Adapter CAR (AdCAR) system. AdCAR-T are redirected to surface antigens via biotin-labeled adapter molecules in the context of a specific linker structure, referred to as Linker-Label-Epitope. AdCAR-T execute highly specific and controllable effector function against a multiplicity of target antigens. In mice, AdCAR-T durably eliminate aggressive lymphoma. Importantly, AdCAR-T might prevent antigen evasion by combinatorial simultaneous or sequential targeting of multiple antigens and are capable to identify and differentially lyse cancer cells by integration of adapter molecule-mediated signals based on multiplex antigen expression profiles. In consequence the AdCAR technology enables controllable, flexible, combinatorial, and selective targeting.