Screening for antibodies against the AMPA receptor is used in patients with suspected paraneoplastic syndromes especially in the case of autoimmune encephalitis.
Antibodies against the AMPA receptor can be observed in paraneoplastic syndrome and classic autoimmune encephalitis but have also been described in cases of isolated psychoses. There are relatively few published cases, 90% of which are women. The age of the patients at the time of diagnosis was 38-87 years (mean 60 years). Antibodies have been associated with tumors (lung, breast, and thymus) in 70% of cases. Antibodies can occur along with other autoantibodies in 60% of cases (antibodies against ANA, GAD-65, cardiolipin, VGCC, SOX1, CV2 / CRMP5, and TPO antigens).
AMPA receptors belong to the group of extracellular antigens. In general, immunotherapy is often more effective in autoantibodies directed against extracellular antigens than in autoantibodies against intracellular antigens. The antibody titer against the AMPA receptor can be used to monitor the efficacy of treatment.
The AMPA receptor (a-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) is an ionotropic glutamate receptor in the CNS. The AMPA receptor test antigen consists of 2 subunits, GluA1 and GluA2, with a molecular weight of approximately 100 kDa each.