CD21 primes extrafollicular differentiation of autoreactive B cells in a TLR7-driven lupus model
Bibliographic record
Abstract
The extrafollicular (EF) B cell differentiation pathway has emerged as a prominent source of autoantibody-secreting cells (ASCs) in systemic lupus erythematosus (SLE). CD21 lo CD11c + B cells are associated with aging, infection, and autoimmunity. They are key contributors to EF ASCs, yet their developmental trajectory and receptor programming are unclear. To study EF mechanics of autoreactive B cells, we adoptively transferred naïve B cell populations into 564Igi mice, which act as an autoreactive host enriched for autoantigens and T cell help. Time-resolved analyses revealed a Toll-like receptor 7 (TLR7)–dependent early escape of peripheral tolerance and a pre–ASC division program. We identified naïve-derived CD21 lo cells as precursors of EF ASCs exhibiting elevated reliance on TLR7. Repertoire analysis delineated protoautoreactive B cell selection and receptor evolution toward self-reactivity. Continuous complement receptor 2 (CR2/CD21)–complement C3d and CD21–complement iC3b engagement triggered receptor down-regulation before proliferation. We reveal CD21 as an initiator of TLR7-dependent autoimmune EF proliferation and target for suppressing autoreactivity.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.003 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".