Dynamic equilibrium of B7-1 dimers and monomers is important for regulation of TCR/CD28 – mediated T cell activation (33.28)
Bibliographic record
Abstract
Abstract Under steady state conditions, B7-1 is present as a mixed population of non-covalent dimers and monomers on the cell surface. Here we have examined the physiological significance of this unique dimer-monomer equilibrium state of B7-1. We demonstrate that altering B7-1 to uniformly covalent dimeric state results in increased frequency of CD28 mediated T cell-APC conjugates. This augmented T cell-APC conjugate formation correlates with persistent concentration of signaling molecules, PKC-θ and lck, at the immunological synapse (IS) and with a higher calcium flux in T cells. In contrast, B7-1 acquisition by T cells, an event that occurs as a consequence of CD28 engagement with B7-1/B7-2, is highly reduced when B7-1 is present in covalently dimeric state. The ability of covalently dimeric and wild type B7-1 to costimulate antigen-specific T cell proliferation was also assessed. In contrast to the enhanced ability of dimeric B7-1 to support proximal T cell activation events, sensitivity to competitive inhibition by soluble CTLA-4:Ig indicated that the covalent dimeric form of B7-1 is in fact less efficient in costimulating T cell proliferation. These findings suggest a novel model in which optimal T cell costimulatory function of B7-1 requires CD28 engagement by B7-1 in a non-covalent dimeric state, followed by dissociation of these B7-1 dimers, facilitating downregulation of CD28 and internalization of B7-1.
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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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".