Reviewed by Sarah Alter, Ph.D. — Scientific Affairs, OrganaBio. 15 years of immunology research spanning autoimmunity, cancer, and infectious disease. University of Miami Miller School of Medicine. Registered Patent Agent.
Chronic inflammatory demyelinating polyneuropathy (CIDP) is the most common chronic autoimmune neuropathy, affecting approximately 1-9 per 100,000 persons, and is characterized by progressive or relapsing proximal and distal limb weakness with sensory involvement. The therapeutic landscape has expanded significantly: IVIG, corticosteroids, and plasma exchange are the established standards; efgartigimod (FcRn inhibitor, ADHERE trial approval 2024) represents the first mechanism-specific approval; and rituximab, BTK inhibitors, and complement inhibitors are in active investigation. The heterogeneity of CIDP — classic versus paranodal antibody-positive subtypes — means that peripheral blood immune profiling requires subtype-aware cohort selection.
Classic CIDP Versus Paranodal Antibody-Positive CIDP: Critical Subtype Distinctions
Approximately 85-90% of CIDP cases are “classic” or antibody-seronegative (for known paranodal antigens). In classic CIDP, the mechanism involves T cell-mediated and macrophage-mediated demyelination of peripheral nerve myelin, with complement activation from IgG1/IgG3 antibodies against currently uncharacterized nodal antigens. Classic CIDP responds to IVIG and corticosteroids.
Approximately 10-15% of CIDP carries IgG4-dominant antibodies against paranodal/nodal proteins:
- Anti-NF155 (neurofascin-155): IgG4 dominant; disrupts the paranodal axoglial junction, producing a distinct clinical phenotype (tremor, cerebellar ataxia, young onset). IVIG-non-responsive but rituximab-responsive.
- Anti-CNTN1 (contactin-1): IgG4 dominant; paranodal disruption; associated with nephrotic syndrome in some cases. Rituximab-responsive.
- Anti-CASPR1 (contactin-associated protein 1): IgG4 dominant, often anti-CNTN1/CASPR1 dual positive; associated with painful CIDP variant. Rituximab-responsive.
The IgG4 dominance of paranodal antibody-positive CIDP produces a complement-independent (non-lytic) mechanism where paranodal protein function is disrupted by steric interference — directly analogous to the IgG4 mechanism in MuSK+ MG and pemphigus vulgaris. For FcRn pharmacodynamics and IgG4-specific research, antibody-positive CIDP is the appropriate disease context.
FcRn Pharmacodynamics Following Efgartigimod Approval
Efgartigimod’s ADHERE trial approval in CIDP makes FcRn the most recently validated therapeutic target in this disease. PBMC-based pharmacodynamic endpoints for FcRn inhibitor development in CIDP include:
- Monocyte FcRn expression: CD14+ monocytes are the primary FcRn-expressing PBMC type; FcRn (FCGRT) mRNA and surface expression quantification in CIDP versus healthy donor monocytes establishes the disease-context baseline
- IgG recycling inhibition: Total IgG catabolism rate acceleration in CIDP monocyte culture systems under FcRn inhibitor treatment
- IgG4-specific FcRn dynamics: In anti-NF155/CNTN1-positive CIDP, the IgG4 subclass FcRn binding kinetics (lower affinity at pH 6 vs. IgG1) produce distinct catabolism dynamics — measuring IgG4-specific vs. total IgG reduction pharmacodynamics requires antibody-subtype-stratified CIDP donor material
T Cell Profile in Classic CIDP
Classic CIDP shows a Th1/Th17-dominant CD4+ T cell profile in peripheral blood, with elevated IFN-gamma and IL-17A producing CD4+ T cells and activated CD8+ T cells. Key features measurable in CIDP PBMCs:
- Elevated CXCR3+CD4+ Th1 cells consistent with IFN-gamma-driven peripheral nerve inflammation
- Th17/Treg imbalance — Treg deficiency correlates with disease activity and IVIG non-response in some cohorts
- CD4+CD28null T cells (a pathogenic effector T cell population with NK-like cytotoxicity) are elevated in CIDP and may contribute to complement-independent nerve damage
Complement Pathway and B Cell Contributions
In classic CIDP, IgG1/IgG3 antibodies against uncharacterized nodal antigens activate complement via the classical pathway, producing C3d deposition on Schwann cells and MAC-mediated myelin damage. Circulating monocytes in classic CIDP show elevated C5aR1 expression and enhanced C5a responsiveness — paralleling the monocyte complement activation profile seen in ANCA vasculitis. B cell contributions include BAFF elevation and elevated plasmablast frequencies in active disease, with IgG1/IgG3-isotype autoantibody production against currently-being-characterized nodal antigens.
Research Applications
- FcRn inhibitor pharmacodynamics: Monocyte FcRn expression, IgG recycling inhibition, IgG4-specific catabolism dynamics in antibody-positive CIDP
- IgG4 mechanism studies: Paranodal protein function disruption mechanisms, IgG4 FcRn affinity characterization, IgG4 class-switching pharmacodynamics in anti-NF155/CNTN1 B cell cultures
- Rituximab and CD20-depletion pharmacodynamics: B cell depletion kinetics, paranodal antibody titer reduction, antibody-positive CIDP B cell characterization
- Complement inhibitor development: C5aR1 expression, C5a-driven monocyte activation, terminal complement complex generation in classic CIDP PBMCs
- T cell profiling: Th1/Th17 characterization, CD4+CD28null T cell enumeration, Treg quantification and IVIG response correlation
OrganaBio CIDP Donor Collection Specifications
- Diagnosis by EFNS/PNS 2010 criteria; INCAT disability score documented
- Paranodal antibody status: anti-NF155, anti-CNTN1, anti-CASPR1 testing documented; IgG subclass for antibody-positive donors
- IVIG response history documented: responsive, IVIG-dependent, IVIG-non-responsive
- Efgartigimod treatment history documented for post-approval cohorts
- Disease state: active relapse versus stable remission documented
- Same-day processing from apheresis; 30-minute standard for fresh material; >80% post-thaw viability
- Available as isolated PBMCs, leukopaks, or fresh whole blood
Related resources: NMOSD Donor PBMCs: AQP4-IgG biology and complement-mediated demyelination | Myasthenia Gravis Donor PBMCs: FcRn and IgG4 (MuSK+) biology