Detection of anti-pituitary autoantibodies by immunoblotting

A new approach to the detection of anti-pituitary autoantibodies by immunoblotting is presented. This method distinguishes pituitary membrane fraction from cytosolic fraction autoantigens and characterizes them by their molecular weight. A 45 kDa pituitary specific membrane protein was identified as an autoantigen in one of 19 patients with idiopathic growth hormone deficiency and the empty sella syndrome. A 43 kDa membrane protein in pituitary and brain was identified as an autoantigen in one other patient with idiopathic growth hormone deficiency and in one of 14 patients with secondary growth hormone deficiency. These autoantibodies were not seen in any of 27 control subjects. Anti-pituitary autoantibodies can be demonstrated by immunoblotting at titres of up to 1/1000. We conclude that immunoblotting is a useful method for the detection of anti-pituitary autoantibodies.