Calcium‐dependent <scp>HLA</scp>‐<scp>DQ</scp> epitope revealed by <scp>EDTA</scp> mediated inhibition of antibody reactions in the Luminex single antigen bead assay
Bibliographic record
Abstract
Complement mediated interference with the detection of antibodies targeting HLA is a known limitation of the single antigen bead (SAB) Luminex assay. Ethylenediaminetetraacetic acid (EDTA) is currently the serum treatment of choice in most histocompatibility laboratories to block complement activation by chelating calcium. The purpose of this study was to investigate a serum with an antibody reactivity to HLA‐DQ6, 7, 8 and 9 molecules, in the Luminex SAB assay, that was inhibited by treatment with EDTA. Serum was from a 55‐year‐old highly sensitised female renal transplant candidate that contained, among others, antibodies to an epitope containing the 74EL eplet, shared by HLA‐DQ6, DQ7, DQ8 and DQ9 molecules. Serum samples were treated with EDTA, dithiothreitol (DTT), or heat prior to testing by SAB assay. EDTA‐treated serum was also tested after the addition of calcium chloride (CaCl 2 ). HLA‐DQ‐specific antibodies were isolated by adsorption/elution method using three informative donor cells and were tested in the absence or presence of EDTA. The antibody reactivity against HLA‐DQ6, DQ7, DQ8 and DQ9 in the SAB assay was significantly inhibited by treating serum and eluates with EDTA and was restored by addition of CaCl 2 . The study represents the first description of a calcium‐dependent epitope in HLA molecules. The relevance of this finding is that the treatment of sera with EDTA could lead to false‐negative reactions in the SAB assay, which may compromise virtual crossmatching.
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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 | 0.002 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 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".