Goat anti Human J chain of dimeric IgA

The reactivity of the antiserum is restricted to J chain as tested in immunoelectrophoresis and radial immunodiffusion. The antiserum shows a single precipitation reaction with totally reduced and alkylated polyclonal and monoclonal polymeric IgA and IgM. No reaction is obtained with the intact polyclonal or monoclonal IgA, IgM and IgG. There is also no detectable reaction with normal human serum, normal human milk, purified Ig heavy and light chains and secretory component. However a single precipitin line can be obtained with human serum after two hours incubation with 9 M urea and 0.2 M mercaptoethanol at pH 8.6, and this shows a reaction of identity with the precipitin line obtained with the purified immunogen. In precipitating techniques as immunoelectrophoresis and single and double radial immunodiffusion to identify the presence of free J chain in human serum or other body fluids and to determine its concentration. Since the J chain is folded within the polymeric structure of the immunoglobulin its epitopes are exposed only to a very limited degree. Although the antiserum may react with epitopes of the intact polymeric immunoglobulin, this will be normally not lead to a visible precipitation. When used in agar gel immunodiffusion, special consideration should be given to the small molecular size of the J chain, which results in a rapid diffusion into the gel layer. To prevent the development of an antigen excess during the second step of the immunoelectrophoresis, the antiserum should be applied immediately after the electrophoresis of the test sample. In double radial immunodiffusion (Ouchterlony) the antiserum should be applied first, followed by free J chain or reference preparation. Normal human serum can be used as a negative control.