284 ANTIBODIES TO LUTEINIZING HORMONE IN A PATIENT TREATED WITH GROWTH HORMONE

Abstract

Many clinical grade preparations of hGH (human growth hormone) are contaminated with hLH and hFSH. However, no evidence of a clinical effect of such contamination has been described. We report the development of antibodies to hLH in a patient treated with hGH for isolated GH deficiency. J.C. was first investigated for short stature at 7-11/12 years and GH therapy was begun at 8-9/12 years for a diagnosis of isolated GH deficiency. On LRF (luteinizing hormone releasing factor) testing, the LH rose from 0.8 to 1.2 ng/ml (LER 960); FSH response also was normal. At 11-11/12 years the patient was still prepubertal with undetectable testosterone levels. A repeat LRF test revealed an “apparent” basal plasma LH of 25.4 ng/ml. Further studies indicated that his serum had antibodies to hLH which have persisted for over 2-1/2 years on growth hormone therapy without the development of significant GH antibodies. 125I-hLH was bound to his serum in a displacable fashion; hFSH and hTSH displaced this tracer only at doses compatible with contamination of these standards by hLH. Radioiodinated hFSH, hTSH and hLH-α were not bound; the antibody is directed against the LH-β subunit. The binding capacity of the serum and the equilibrium constant for the binding reaction are sufficiently great to be physiologically significant.