Platelet Factor 4 Antibody Persistence and Long-term Pathogenicity in Vaccine-induced Immune Thrombotic Thrombocytopenia
Bibliographic record
Abstract
BACKGROUND: Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a transient prothrombotic process, although recent data suggest that VITT anti-platelet factor 4 (PF4) antibodies are more persistent than those in heparin-induced thrombocytopenia. OBJECTIVES: We sought to interrogate whether anti-PF4 antibody persistence in VITT is related to the continued persistence of antibody clones from the acute phase or to the development of novel anti-PF4 antibodies due to epitope spreading. METHODS: Samples from 6 patients with Ad26.COV2.S-associated VITT with a median time to follow-up of 244 days from acute presentation (range, 114-664 days) were studied in antigenic/functional assays and by mass spectrometry. One patient with ChAdOx1 nCoV-19-associated VITT was tested >4 years after acute presentation. RESULTS: Upon affinity-enrichment of anti-PF4 antibodies, mono/oligoclonal anti-PF4 antibodies were observed despite negative results in serum protein electrophoresis/"Mass-Fix" testing of native sera. Anti-PF4 antibody abundance decreased over time, with no evidence of novel anti-PF4 antibody production after acute presentation. Although previous studies indicate a stereotypical pairing of VITT antibodies with lambda light chains, 1 patient with VITT produced antibodies with a kappa light chain. Long-term thrombocytopenia/thrombosis was not seen in any of the 6 Ad26.COV2.S-associated VITT patients; however, platelet-activating anti-PF4 antibodies were seen 4 years after the acute event in an additional patient with ChAdOx1 nCoV-19-associated VITT with chronic low-grade thrombocytopenia. CONCLUSION: VITT, unlike monoclonal gammopathy of thrombotic significance, appears to be a monoclonal gammopathy of unknown significance-negative state, but it needs confirmation in larger studies. VITT antibodies can be composed of lambda or kappa light chains, and some patients with VITT exhibit persistent thrombocytopenia many years after the acute event.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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 | 0.000 |
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 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".