THE EARLY ANTIBODY RESPONSE TO HUMAN GROWTH HORMONE

The development of antibodies to human growth hormone (HGH) was studied in three growth hormone deficient patients utilizing specific antisera to Ig G and Ig M immunoglobulins. At 2½ weeks after beginning growth hormone administration binding of HGH131I to Ig M (12.1–16.3 %) and Ig G (8.8–11.2 %) immunoglobulins was demonstrated. At 13 weeks after the onset of therapy binding to Ig M had decreased (7.2-9.4 %) and the binding to Ig G had increased (11.2–15.7 %). The binding of HGH131I to immunoglobulins was inhibited by unlabelled HGH. These findings, which are typical of the sequential development of antibodies of different immunoglobulin classes seen in the early antibody response, strengthen the concept that the binding of HGH131I to plasma proteins observed in response to HGH therapy represents the development of specific antibody.