Autoantibodies in chronic pain
| IgG antibody | Antigen | Oncologic associations | Pain and other neural associations |
| Autoantibodies with strong evidence of pain causality | |||
| Nodal complex IgGs | LGI1, CASPR2, CASPR1 | Infrequent: thymoma | Isaacs’ and Morvan’s syndromes include autonomic and muscle hyperexcitability, pain only |
| GAD65 IgG | GAD65 | Infrequent: thymoma; renal cell, breast, colon, lung | Dysautonomia with and without pain, myelopathy and spasticity (stiff person syndrome), cerebellar disease |
| Amphiphysin IgG | Amphiphysin | Frequent: lung, breast, ovarian | Focal or diffuse pain, neuropathy, myelopathy, encephalopathy, cerebellar syndrome |
| Glycine-receptor IgG | Glycine receptor-gated chloride channel receptor (alpha1) | Infrequent: breast, thymoma, Hodgkin’s | Pain, brainstem, ataxia, seizures, with progressive encephalomyelitis with rigidity and myoclonus (PERM) or stiff person syndrome |
| NMO IgG | Aquaporin-4 | Infrequent: breast, thymoma, lymphoma | Rare root and muscle involvements, painful spasms |
| Autoantibodies associated with pain with less certain causality | |||
| Voltage-gated calcium channel IgG | N-type and P/Q-type VGCC | Carcinomas: lung, breast or gynaecological (less frequent with P/Q type) | Hyperexcitable nerve disorders, including cramp fasciculation, myelopathy and varieties of neuropathy (somatic, sudomotor, painful) |
| Neuronal ganglionic AChR IgG (alpha-3) | Neuronal AChR containing alpha-3 subunits | Adenocarcinoma, thymoma, small cell carcinoma | Pandysautonomic neuropathy, including with Adies pupil, somatic neuropathies, painful small fibre; hyperexcitable nerve disorders |
| Adrenergic receptor IgG | β2-adrenergic receptor, muscarinic-2 receptor, alpha-1a adrenoreceptors | Cancer not described with pain only | Complex regional pain syndrome-1 |
Modified from Klein CJ with permission. Autoimmune Neurology: Autoimmune-mediated peripheral neuropathies and autoimmune pain 2016.15
AChR, acetylcholine receptor; CASPR, contactin-associated protein; GAD, glutamic acid decarboxylase; LGI1, leucine-rich glioma-inactivated 1 protein; NMO, neuromyelitis optica; VGCC, voltage-gated calcium channel.