Provided is a method of bioassay for the quantification of peptide fragments elevated in lung diseases such as COPD, SCC, or IPF. The peptide fragments comprise a neo-epitope formed at a cleavage site by cleavage in vivo of elastin by a proteinase. In the method a sample is contacted with an antibody having specific binding affinity for the neo-epitope amino acid sequence and determining the level of binding is determined where the antibody binds one of the following terminal sequences: . . . FGPGVV, . . . VPGLGV or IKAPKL . . . . Also provided are antibodies and immunoassay kits for use in such methods.