Jintropin is made of amino acids all joined together. Its important to realise that there were originally two forms of man made HGH. One of the manufacturing processes made a form of HGH which was slightly diiferent than the HGH we produce naturally in our bodies. This HGH contained 192 amino acids which is not the same as he natural 191 amino acid HGH we produce in our own bodies. This led to some adverse reactions as the body didnt recognise this hormone and mounted an immune response against it. Jintropin contains 191 amino acid HGH. The 191 version of HGH is the correct type of growth hormone to take. You will have no rejection problems with Jintropin as its the same hormone that we see in our bodies.