System-wide immunoregulation by polyvalent IgG: integrating transcriptomic, miRNA, and proteomic landscapes

BACKGROUND: Polyvalent IgG (pIgG/IVIg), derived from thousands of donors, exerts broad immunomodulatory effects; however, its direct cellular targets and genome-wide regulatory impacts remain incompletely defined. METHODS: Peripheral blood mononuclear cells (PBMCs) from 20 healthy donors were cultured for 72 h with pIgG (100 µg/mL) or mock conditions. Cell viability, phenotype, memory subsets, chemokine receptors, and intracellular cytokines were assessed by flow cytometry. Differential gene expression, miRNA/sRNA profiles, and pathway enrichments were analyzed by RNA-seq and small-RNA sequencing. Proteome-wide IgG binding was mapped using human proteome microarrays across lymphoid subsets, and pathogen-derived linear epitope recognition was evaluated using a 4,345-epitope infectious-disease microarray. RESULTS: pIgG preserved PBMC viability but significantly modulated immune function: it reduced IL-17⁺ CD4⁺ T cells and tissue-resident memory T cells, decreased IL-4⁺ CD8⁺ T cells, enhanced IFN-γ⁺ γδ T cells, downregulated CCR5 and CCR6, and expanded IL-10⁺ B cells while reducing IL-13⁺ and IL-17⁺ B cells. Transcriptomic analysis revealed 4,820 upregulated and 2,160 downregulated genes, with enrichment of MHC class II and TCR-signaling pathways and selective modulation of cytokine, chemokine, CD, and HLA genes. Innate sensors-including TLR4, TLR8, and NLR4-were downregulated. Small-RNA analysis identified 19 differentially expressed miRNAs and 79 novel sRNAs, indicating epigenetic remodeling. Proteome-wide profiling detected ~ 130 IgG-recognized proteins per lymphocyte subset and 180 shared targets enriched in cytosolic, vesicular, and endocytic pathways. Pathogen-epitope profiling identified 948 recognized sequences from 56 viruses, 21 bacteria, and 12 parasites. CONCLUSIONS: pIgG functions as a multilayered immunoregulator that attenuates Th17-associated inflammation, promotes IL-10-mediated regulatory circuits, and modulates receptor signaling and antigen-processing pathways. These findings underscore its potential for broad therapeutic immunomodulation.