[Neuropsychiatric lupus and autoantibodies against ionotropic glutamate receptor (NMDAR)]

Almost half of lupus patients will experience neuropsychiatric symptoms during the course of their disease. The etiology of the neuronal damages are still uncertain and probably multiple. Auto-antibodies reactive with brain have been postulated to play a role. The observation of pathogenic auto-antibodies binding the NR2A and NR2B subunits of the ionotropic glutamate receptor (NMDAR) illustrates this hypothesis.

First studies showed that 40% of lupus patients possess serum titers of anti-NR2A/B antibody, but the presence of these auto-antibodies is not always associated with the occurrence of neuronal damages or neuropsychiatric symptoms. Nevertheless, their presence is observed in the cerebro-spinal fluid (CSF) of one half of the patients suffering from neurolupus. The presence in the serum of these auto-antibodies anti-NR2A/B of the NMDAR is preliminary to their presence in the CSF where their deleterious effect is observable. Their entry into the brain is dependent on a breach of the blood brain barrier (BBB).

In conclusion, the serum titer of auto-antibodies against NR2A/B subunits is an indication of the potential for neuro-psychiatric manifestations during the course of the disease.