{
  "abstract": "Objective Synovial fluid single-cell immunoprofiling is a powerful tool for investigating joint arthropathies. However, cell isolation protocols are yet to be standardised. We compared different cell-isolation protocols across diverse synovial fluid samples, evaluating cell recovery, sample inclusion rate and immune-cell composition.Methods From 48 synovial fluid samples with volumes>2 mL, we performed paired cell isolation of whole synovial fluid cells (WSFCs), with and without hyaluronidase and synovial fluid mononuclear cells (SFMCs) by density-gradient centrifugation. Of these, nineteen paired samples underwent deep immunophenotyping using a 31-marker spectral flow cytometry panel with dimensionality reduction and unsupervised clustering. Immune cell frequencies were quantified across protocols. Synovial fluid rheology was assessed in an additional 23 samples.Results WSFC isolation yielded higher cell recovery and lower sample loss than SFMC isolation, with differences varying with inflammation level. SFMC isolation reduced the sample inclusion rate (the proportion of samples with sufficient cell numbers for downstream profiling) by 50% in low-grade and 10% in high-grade inflammatory samples. Cell recovery correlated with synovial fluid viscosity. Repeated centrifugation alone matched the cell recovery seen with hyaluronidase treatment. Deep immunophenotyping revealed systematic protocol-dependent differences: WSFCs were enriched for CD8+, CD4+ and γδ T cells, while SFMCs contained higher proportions of dendritic cells and classical monocytes. Both methods stratified samples by inflammation, but WSFCs provided superior cellular resolution.Conclusions SFMC isolation excluded low-grade inflammatory samples, introducing bias and reducing statistical power. WSFC-based approaches with hyaluronidase or repeated centrifugation improved recovery and are therefore recommended for synovial fluid immunoprofiling studies.",
  "abstract_shown": true,
  "affiliations": [
    "Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway",
    "Department of Biology, Chair of Genetics, Friedrich-Alexander-Universitat Erlangen-Nurnberg (FAU), Erlangen, Germany",
    "The REMEDY Center, Division of Rheumatology and Research, Diakonhjemmet Hospital, Oslo, Norway",
    "Department of Pharmacy, Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway",
    "Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway"
  ],
  "article_type": "research article",
  "arxiv": null,
  "author_total": 11,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Abel Mekonnen Tesfaye",
      "orcid": "0000-0003-1133-8923"
    },
    {
      "affs": [
        1
      ],
      "name": "Jara Tsegaye Leta",
      "orcid": "0009-0006-4858-4721"
    },
    {
      "affs": [
        0
      ],
      "name": "Danh Phung",
      "orcid": "0009-0000-5570-808X"
    },
    {
      "affs": [
        2
      ],
      "name": "Erlend Holm-Nordli",
      "orcid": "0009-0006-1710-8538"
    },
    {
      "affs": [
        2
      ],
      "name": "Julie Røkke Osen",
      "orcid": "0009-0005-4762-4616"
    },
    {
      "affs": [
        3
      ],
      "name": "Josefine Eilsø Nielsen",
      "orcid": "0000-0001-9274-5533"
    },
    {
      "affs": [
        2,
        4
      ],
      "name": "Hilde Berner Hammer",
      "orcid": "0000-0001-7317-8991"
    },
    {
      "affs": [
        0
      ],
      "name": "Andreas Lossius",
      "orcid": "0000-0002-9640-1954"
    },
    {
      "affs": [
        2
      ],
      "name": "Guro Løvik Goll"
    },
    {
      "affs": [
        2
      ],
      "name": "Silje Watterdal Syversen",
      "orcid": "0000-0003-2159-3696"
    },
    {
      "affs": [
        0
      ],
      "name": "Asbjørn Christophersen",
      "orcid": "0000-0003-4049-807X"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/dwrmc9j3b9wha.bib",
  "cited_by": 0,
  "doi": "10.1136/rmdopen-2026-007291",
  "fulltext_url": "https://rmdopen.bmj.com/content/12/4/e007291.full",
  "id": "dwrmc9j3b9wha",
  "issns": [
    "2056-5933"
  ],
  "landing_url": "https://doi.org/10.1136/rmdopen-2026-007291",
  "language": "en",
  "licence": "CC-BY-NC-4.0",
  "licence_label": "CC BY-NC 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by-nc/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "heading",
      "1506"
    ],
    [
      "heading",
      "Early Arthritis"
    ],
    [
      "heading",
      "Original Research"
    ],
    [
      "lcc",
      "R"
    ],
    [
      "openalex",
      "2745|Rheumatoid Arthritis Research and Therapies"
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  "openalex": "W7223328479",
  "pdf_url": "https://rmdopen.bmj.com/content/12/4/e007291.full.pdf",
  "pmcid": "PMC13711588",
  "pmid": "42919619",
  "published": "2026-10-23",
  "publisher": "BMJ Publishing Group",
  "ris": "https://research.draconitic.com/paper/dwrmc9j3b9wha.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T13:44:15Z",
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  "subjects": [
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      "field": "medicine",
      "origin": "openalex:2745|Rheumatoid Arthritis Research and Therapies",
      "subfield": "general"
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  ],
  "title": "Synovial fluid cell isolation protocol affects immune cell recovery and composition across inflammatory states",
  "title_text": "Synovial fluid cell isolation protocol affects immune cell recovery and composition across inflammatory states",
  "type": "peer-reviewed",
  "updated_at": "2026-10-31T12:22:20Z",
  "url": "https://research.draconitic.com/paper/dwrmc9j3b9wha",
  "venue": "RMD Open",
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}