This antibody reacts to the heavy chain of human IgG4. No cross reactivity with human IgG1, IgG2, IgG3, IgM, IgA, IgD, IgE, monkey (Cyno or Rhesus) IgG, mouse IgG, rat IgG, or goat IgG. Recombinant rabbit monoclonal antibodies are produced using in vitro