Uncoupling CD21 and CD19 of the B-cell coreceptor
Bibliographic record
Abstract
Complement receptors (CRs) CD21 and CD35 form a coreceptor with CD19 and CD81 on murine B cells that when coligated with the B-cell receptor lowers the threshold of activation by several orders of magnitude. This intrinsic signaling role is thought to explain the impaired humoral immunity of mice bearing deficiency in CRs. However, CRs have additional roles on B cells independent of CD19, such as transport of C3-coated immune complexes and regulation of C4 and C3 convertase. To test whether association of CR with CD19 is necessary for their intrinsic activation-enhancing role, knockin mice expressing mutant receptors, Cr2(Delta/Deltagfp), that bind C3 ligands but do not signal through CD19 were constructed. We found that uncoupling of CR and CD19 significantly diminishes survival of germinal center B cells and secondary antibody titers. However, B memory is less impaired relative to mice bearing a complete deficiency in CRs on B cells. These findings confirm the importance of interaction of CR and CD19 for coreceptor activity in humoral immunity but identify a role for CR in B-cell memory independent of CD19.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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 source (direct Gemma or distilled Codex), 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".