{
  "abstract": "Background/objectives\n\nRegulatory rheumatoid factor (regRF) is a recently discovered population of natural anti-idiotypic antibodies carrying a shared paratope specific to the PD-1 molecule. Normally, regRF exerts a cytotoxic effect on PD-1-expressing T lymphocytes, including autoreactive ones, thereby controlling their expansion. The specificity for PD-1 indentifies regRF as a promising therapeutic agent for suppressing autoimmune reactions via the PD-1 pathway. The aim of this study was to develop gentle methods for regRF isolation from healthy blood plasma, which would preserve the bioactivity of regRF.Methods\n\nAmmonium sulfate precipitation was used for crude regRF purification. A search for suitable affinity sorbents was carried out. The purified regRF was tested for its bioactivity.Results\n\nAmmonium sulfate precipitation at 35% saturation, followed by extraction with 28% saturated ammonium sulfate solution, allowed the separation of regRF from a portion of non-target IgG and high-molecular-weight fibrinogen. RegRF showed high affinity for Cibacron Blue and no binding to Protein A. Sequential affinity chromatography on immobilized Cibacron Blue and Protein A enabled the purification of regRF from non-target immunoglobulins and low-molecular-weight fibrinogen. The purified regRF samples showed binding to PD-1 and reduced the PD-1+CD4+ T lymphocyte count in vitro.Conclusions\n\nThus, we have identified sorbents and conditions for the purification of biologically active regRF.",
  "abstract_shown": true,
  "affiliations": [
    "Laboratory of Molecular and Cellular Immunology, Department of Immunology and Cell Biology, Udmurt State University, 1 Universitetskaya St, Izhevsk 426034, Russia.",
    "Department of Physical and Colloid Chemistry, Peoples' Friendship University of Russia Named After Patrice Lumumba (RUDN University), 6 Miklukho-Maklaya St, Moscow 117198, Russia.",
    "Laboratory of Biocompatible Materials, Udmurt Federal Research Center UB RAS, 34 T. Baramzinoy St, Izhevsk 426067, Russia."
  ],
  "article_type": "research article",
  "arxiv": null,
  "author_total": 5,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Daria Menshikova"
    },
    {
      "affs": [
        0,
        2
      ],
      "name": "Alexey Terentiev"
    },
    {
      "affs": [
        0
      ],
      "name": "Pavel Ivanov"
    },
    {
      "affs": [
        1
      ],
      "name": "Alexandr Cherednichenko"
    },
    {
      "affs": [
        0,
        2
      ],
      "name": "Liubov Beduleva",
      "orcid": "0000-0002-2515-5960"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/5vvhbk15gekhn.bib",
  "cited_by": 0,
  "doi": "10.3390/antib15050098",
  "fulltext_url": "https://europepmc.org/articles/PMC13700785",
  "id": "5vvhbk15gekhn",
  "issns": [
    "2073-4468"
  ],
  "landing_url": "https://europepmc.org/article/MED/42930040",
  "language": "eng",
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "2741|Monoclonal and Polyclonal Antibodies Research"
    ]
  ],
  "openalex": "W7222944943",
  "pdf_url": "https://europepmc.org/articles/PMC13700785?pdf=render",
  "pmcid": "PMC13700785",
  "pmid": "42930040",
  "published": "2026-10-19",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/5vvhbk15gekhn.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:22:01Z",
      "native_id": "MED:42930040",
      "source": "europepmc",
      "url": "https://europepmc.org/article/MED/42930040"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "openalex:2741|Monoclonal and Polyclonal Antibodies Research",
      "subfield": "imaging"
    }
  ],
  "title": "Purification of Bioactive Natural Antibodies to PD-1 Known as Regulatory Rheumatoid Factor from Human Blood Plasma.",
  "title_text": "Purification of Bioactive Natural Antibodies to PD-1 Known as Regulatory Rheumatoid Factor from Human Blood Plasma.",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:22:01Z",
  "url": "https://research.draconitic.com/paper/5vvhbk15gekhn",
  "venue": "Antibodies (Basel, Switzerland)",
  "versions": []
}