Lymph nodes orchestrate adaptive immune responses, with germinal centers enabling affinity maturation and plasma cell formation. Here, we present a protocol for rapid, high-resolution, multicolor 3D imaging of whole immunized mouse lymph nodes. We describe steps for immunization, lymph node harvesting, fixation, permeabilization, staining, and clearing. We cover image acquisition using a light sheet fluorescence microscope and analysis using the Imaris software. This protocol allows the quantification of germinal center B cells, plasma cells, and follicular T cells at single-cell resolution.
Copyright © 2025 The Author(s). Published by Elsevier Inc. All rights reserved.

In B cells, BLIMP1 is required for plasma cell differentiation. BLIMP1 is also expressed in some germinal center (GC) B cells (GCBC), yet the role of BLIMP1 in GCBC is not understood. Here we generated mixed bone marrow (BM) chimeric mice using Prdm1+/+ CD19Cre and Prdm1fl/fl CD19Cre BM, allowing us to examine the cell-intrinsic functions of BLIMP1 in GCBC, independent of antibody or antigen levels. Strikingly, BLIMP1-deficient B cells quickly dominate GCs and persist for a much longer time compared with wild-type cells. BLIMP1 deficiency promotes positive selection of GCBCs and enhances cell-cycle progression. Additionally, BLIMP1 deficiency alters class switching and memory B cell generation from GCBCs. Mechanistically, BLIMP1-deficient GCBCs fail to downregulate BCL6 and to upregulate IRF4, indicating that BLIMP1 controls the expression of these transcription factors that mediate exit from the GC. These studies revealed unique functions of BLIMP1 in regulating GCBC responses that impact long-lived immune compartments.
Copyright © 2025 The Author(s). Published by Elsevier Inc. All rights reserved.

Whole-exome sequencing of two unrelated kindreds with systemic autoimmune disease featuring antinuclear antibodies with IgG4 elevation uncovered an identical ultrarare heterozygous TNIP1Q333P variant segregating with disease. Mice with the orthologous Q346P variant developed antinuclear autoantibodies, salivary gland inflammation, elevated IgG2c, spontaneous germinal centers and expansion of age-associated B cells, plasma cells and follicular and extrafollicular helper T cells. B cell phenotypes were cell-autonomous and rescued by ablation of Toll-like receptor 7 (TLR7) or MyD88. The variant increased interferon-β without altering nuclear factor kappa-light-chain-enhancer of activated B cells signaling, and impaired MyD88 and IRAK1 recruitment to autophagosomes. Additionally, the Q333P variant impaired TNIP1 localization to damaged mitochondria and mitophagosome formation. Damaged mitochondria were abundant in the salivary epithelial cells of Tnip1Q346P mice. These findings suggest that TNIP1-mediated autoimmunity may be a consequence of increased TLR7 signaling due to impaired recruitment of downstream signaling molecules and damaged mitochondria to autophagosomes and may thus respond to TLR7-targeted therapeutics.
© 2024. The Author(s).

Peripheral CD8+ T cell tolerance is a checkpoint in both autoimmune disease and anti-cancer immunity. Despite its importance, the relationship between tolerance-induced states and other CD8+ T cell differentiation states remains unclear. Using flow cytometric phenotyping, single-cell RNA sequencing (scRNA-seq), and chromatin accessibility profiling, we demonstrated that in vivo peripheral tolerance to a self-antigen triggered a fundamentally distinct differentiation state separate from exhaustion, memory, and functional effector cells but analogous to cells defectively primed against tumors. Tolerant cells diverged early and progressively from effector cells, adopting a transcriptionally and epigenetically distinct state within 60 h of antigen encounter. Breaching tolerance required the synergistic actions of strong T cell receptor (TCR) signaling and inflammation, which cooperatively induced gene modules that enhanced protein translation. Weak TCR signaling during bystander infection failed to breach tolerance due to the uncoupling of effector gene expression from protein translation. Thus, tolerance engages a distinct differentiation trajectory enforced by protein translation defects.
Copyright © 2024 Elsevier Inc. All rights reserved.

Follicular lymphoma (FL) is a generally incurable malignancy that evolves from developmentally blocked germinal center (GC) B cells. To promote survival and immune escape, tumor B cells undergo significant genetic changes and extensively remodel the lymphoid microenvironment. Dynamic interactions between tumor B cells and the tumor microenvironment (TME) are hypothesized to contribute to the broad spectrum of clinical behaviors observed among FL patients. Despite the urgent need, existing clinical tools do not reliably predict disease behavior. Using a multi-modal strategy, we examined cell-intrinsic and -extrinsic factors governing progression and therapeutic outcomes in FL patients enrolled onto a prospective clinical trial. By leveraging the strengths of each platform, we identify several tumor-specific features and microenvironmental patterns enriched in individuals who experience early relapse, the most high-risk FL patients. These features include stromal desmoplasia and changes to the follicular growth pattern present 20 months before first progression and first relapse.
Published by Elsevier Inc.