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Unit Code 84300:
Neuroimmunology Antibody Follow-up, Serum

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Useful For

Monitoring patients who have previously tested positive for

paraneoplastic autoantibodies utilizing #83380 "Paraneoplastic

Autoantibody Evaluation, Serum"

Clinical Information

Paraneoplastic autoimmune neurological disorders reflect a

patient's humoral and cellular immune responses to cancer. The

cancer may be new or recurrent, is usually limited in metastatic

volume, and is often occult by standard imaging procedures.

Autoantibodies specific for onconeural proteins found in the plasma

membrane, cytoplasm, and nucleus of neurons or muscle are

generated in this immune response and serve as serological markers

of paraneoplastic autoimmunity. The most commonly recognized

cancers in this context are small-cell lung carcinoma (SCLC),

thymoma, ovarian (or related mullerian) carcinoma, breast carcinoma,

and Hodgkin's lymphoma. Pertinent childhood neoplasms recognized

thus far include neuroblastoma, thymoma, Hodgkin's lymphoma, and

chondroblastoma. An individual patient's autoantibody profile can

predict a specific neoplasm with 90% certainty, but not the neurological

syndrome.

 

Four classes of autoantibodies are recognized:

1.   Neuronal nuclear (ANNA-1, ANNA-2, ANNA-3)

2.   Neuronal and muscle cytoplasmic (PCA-1, PCA-2, PCA-Tr,

      CRMP-5, amphiphysin, and striational)

3.   Glial nuclear (AGNA)

4.   Plasma membrane cation channel Antibodies (neuronal P/Q-type

      and N-type calcium channel and muscle acetylcholine receptor

      autoantibodies). These autoantibodies are potential effectors of

      neurological dysfunction.

 

Seropositive patients usually present with subacute neurological

symptoms and signs. The patient may present with encephalopathy,

cerebellar ataxia, myelopathy, radiculopathy, plexopathy, sensory,

sensorimotor, or autonomic neuropathy, with or without coexisting

evidence of a neuromuscular transmission disorder:  Lambert-Eaton

syndrome (LES), myasthenia gravis, or neuromuscular hyperexcitability.

Initial signs may be subtle, but a subacute multifocal and progressive

syndrome usually evolves. Sensorimotor neuropathy and cerebellar

ataxia are common presentations, but the clinical picture in some

patients is dominated by striking gastrointestinal dysmotility, limbic

encephalopathy, basal ganglionitis, or cranial neuropathy (especially

loss of vision, hearing, smell, or taste). Cancer risk factors include past

or family history of cancer, history of smoking or social/environmental

exposure to carcinogens. Early diagnosis and treatment of the

neoplasm favor less neurological morbidity and offer the best hope

for survival.

Reference Values

NEURONAL NUCLEAR ANTIBODIES

Antineuronal Nuclear Antibody-Type 1 (ANNA-1)

      <1:240  

Antineuronal Nuclear Antibody-Type 2 (ANNA-2)  

      <1:240

Antineuronal Nuclear Antibody-Type 3 (ANNA-3)

      <1:240

 

NEURONAL AND MUSCLE CYTOPLASMIC ANTIBODIES

Purkinje Cell Cytoplasmic Antibody, Type 1 (PCA-1)

      <1:240

Purkinje Cell Cytoplasmic Antibody, Type 2 (PCA-2)

      <1:240

Purkinje Cell Cytoplasmic Antibody, Type Tr  (PCA-Tr)

      <1:240

Amphiphysin Antibody

      <1:240

CRMP-5-IgG

      <1:240

Striational (Striated Muscle) Antibodies

      <1:60

Paraneoplastic Autoantibody Western Blot Confirmation

      Negative

CRMP-5-IgG Western Blot

      Negative

 

CATION CHANNEL ANTIBODIES

N-Type Calcium Channel Antibody

      < or = 0.02 nmol/L

P/Q-Type Calcium Channel Antibody

      < or = 0.02 nmol/L

ACh Receptor (Muscle) Binding Antibody

      < or = 0.02 nmol/L

AChR Ganglionic Neuronal Antibody

      < or = 0.02 nmol/L

ACh Receptor (Muscle) Modulating Antibodies

      0-20% (reported as __% loss of AChR)

 

GAD65 ANTIBODY ASSAY

      < or = 0.02 nmol/L

 

Neuron-restricted patterns of IgG staining that do not fulfill criteria

for amphiphysin, ANNA-1, ANNA-2, ANNA-3, PCA-1, PCA-2, PCA-Tr,

or CRMP-5-IgG may be reported as "unclassified antineuronal IgG."

Complex patterns that include non-neuronal elements may be reported

as "uninterpretable."

Note:   Titers lower than 1:240 are detectable by recombinant

                CRMP-5 Western blot analysis. CRMP-5 Western blot

                analysis will be done on request on stored serum (held 4

                weeks). This supplemental testing is recommended in

                cases of chorea, vision loss, and cranial neuropathy and

                myelopathy. Call the Neuroimmunology Laboratory at

                800-533-1710 or 507-266-5700 to request CRMP-5

Western blot.

Interpretation

Antibodies directed at onconeural proteins shared by neurons, muscle,

and certain cancers are valuable serological markers of a patient's

immune response to cancer. They are not found in healthy subjects

and are usually accompanied by subacute neurological symptoms and

signs. Several autoantibodies have a syndromic association, but no

known autoantibody predicts a specific neurological syndrome.

Conversely, a positive autoantibody profile has 80% to 90% predictive

value for a specific cancer. It is not uncommon for more than 1

paraneoplastic autoantibody to be detected, each predictive of the

same cancer.

Cautions

This test should only be utilized when the presence of paraneoplastic

autoantibodies has been previously documented.

Key