Autoantibodies against eukaryotic translation elongation factor 1 delta (EEF1D) in two patients with autoimmune cerebellar ataxia

To report a novel autoantibody against eukaryotic translation elongation factor 1 delta (EEF1D) in two patients with autoimmune cerebellar ataxia (ACA). The patients on one center with cerebellar ataxia of unknown cause, who were tested positive with tissue-based indirect immunofluorescence assay (TBA) on rat cerebellum sections and negative for comprehensive anti-neural autoantibodies panel, were investigated for novel autoantibody identification. Tissue-immunoprecipitation (TIP) combined with mass spectrometric (MS) analysis was used to identify the target antigen. The EEF1D protein was identified from complex precipitated by serum and cerebrospinal fluid (CSF) of one patient, while the specific binding of autoantibodies and EEF1D were confirmed by subsequent neutralization experiment, recombinant cell-based indirect immunofluorescence assay (CBA) and western blot. In consequently test using CBA, another anti-EEF1D positive ACA patient was identified and confirmed by western blot. All enrolled 30 health doners and 15 connective tissue diseases patients without neurological disorders were anti-EEF1D negative. The two anti-EEF1D positive patients presented similar clinical manifestations, their outcomes supported the effectiveness of immunotherapy, but the cerebellar atrophy occurred before treatment may be irreversible. Symptoms of one patient worsened again after the weaning of pulse corticosteroid therapy. The identification of anti-EEF1D autoantibody provides a new potential biomarker for early diagnosis and recurrence prevention of ACA.