Purification of Bioactive Natural Antibodies to PD-1 Known as Regulatory Rheumatoid Factor from Human Blood Plasma

Background/Objectives: Regulatory 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

Ammonium 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.