Autoantibodies against pituitary peptides in sera from patients with multiple sclerosis

Autoantibodies against pituitary peptides were demonstrated in sera from multiple sclerosis (MS) patients. Ten patients with lupus erythematosus disseminatus (SLE) and 97 healthy blood donors served as controls. The sera were used as primary antibodies in the indirect immuno-enzyme cytochemical (IEC) method, with fixed, paraffin-embedded rat brains and rat and hog pituitaries as antigen substrates. Eleven of the 33 MS sera reacted with peptides in the neural lobe/hypothalamic nuclei or distal lobe. The MS had a significantly higher incidence of peptide antibodies than sera from controls (11/33 vs 9/97). The mean antibody titers were significantly different (1577 vs 333). Comparison with rabbit reference antibodies specific to each of the 6 distal lobe hormones showed that the 9 distal lobe-positive MS sera reacted with cells harboring peptides of the somatotropin family. The presence of peptide autoantibodies was not related to clinical status or medical treatment. No antibodies against pituitary peptides were found in the SLE sera. One of the 11 positive MS sera showed antibodies against gastric parietal cells. None of the 11 sera showed antibodies against muscle, mitochondria, thyroid, adrenal, or parotid antigens. We propose that in a proportion of patients with MS, these autoantibodies might be involved in the demyelinization process by interfering with the peptide/receptor interplay, thus placing MS as a disease in analogy with myasthenia gravis. Alternatively, these autoantibodies might be involved in the altered immunoregulation of MS or be secondary to the disease.