Quantitative estimation of dystrophin protein: a sensitive and convenient "two-antibody sandwich" ELISA

As dystrophin protein, the protein product of Duchenne muscular dystrophy (DMD) gene, represents only 0.002 approximately 0.03% of the total muscle proteins and human dystrophin protein has not been purified, quantitative estimation of this protein has been difficult. We describe a sensitive, reliable and convenient "two-antibody sandwich" enzyme-linked immunosorbent assay (ELISA) using commercially available monoclonal antibodies. This system, using a capture antibody specific for carboxyl terminus and two different detection antibodies for the mid-rod domain and the amino-terminal domain, is highly specific for dystrophin, since muscle specimens from DMD patients gave almost zero response (n = 3, 0.38 approximately 0.45%; expressed as a percentage of normal muscle tissue). This assay should prove to be an accessible and useful tool for the diagnosis of DMD/BMD and for the evaluation in clinical trials such as myoblast transfer and gene therapy.