Trinitrophenol (TNP) is an important hapten often used for immunological research. Haptens are small molecules that can elicit an immune response when they are attached to a carrier molecule such as a protein. A TNP-protein conjugate can be injected into an animal model, such as a mouse, so that their immune system can produce anti-TNP antibodies. By measuring changes in the levels of anti-TNP IgM in these animals, scientists can evaluate how pharmacologic or genetic manipulations impact the primary immune response. Signosis offers an ELISA kit to measure mouse anti-TNP IgM.