[The antigenic topography of human growth hormone and the humoral expression of its various epitopes].

Twenty monoclonal antibodies (MAb) against human growth hormone (hGH) were used to establish the antigenic topography of this protein. Mapping experiments were carried out by testing the ability of paired MAb to bind simultaneously or separately to 126I-hGH. Since the specificity of the MAb versus hGH, human placental lactogen, animal prolactins and growth hormones was known, consideration of the whole set of results obtained supported the proposal of a tridimensional model for the antigenic structure of hGH. Further work correlated some of the mapped epitopes with particular regions within the primary structure of the hormone. In addition, it could be demonstrated that certain MAb may induce conformational changes in the antigen as a result of its binding. The humoral expression of various hGH epitopes during the maturation of the immune response was studied in human patients therapeutically treated with hGH and in mice and hamsters submitted to different immunization schemes: chronic administration of the antigen, secondary response and conventional hyperimmunization. The results indicated temporal and individual variations in the titers of each class of Ab as well as the existence of enhancer and heteroclitic Ab. Hence, the expression of the various epitopes of a protein antigen during the immune response is quite probably a stochastic process which depends on individual variations.