Reviewed by the OrganaBio scientific team.
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; Cell Processing and Cryopreservation (CPC) Services average 30 minutes from receipt to first centrifuge spin; >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

