“…The majority of these adverse reactions are believed to have an immunological etiology [3], Based on the hypothesis that drug hypersensitivity arises when drugs, which are low-molecular compounds, become immunogenic after binding irreversibly with mac romolecules [4,5] such as tissue or serum proteins or after polymerization, it is considered that the immune system recognizes drug-protein conjugates and produces drugspecific antibodies [6]. Penicillins have generally been em ployed as a model for drug hypersensitivity in animal sys tems and the major antigenic determinant derived from penicillin has been identified as a protein-conjugated penicilloyl group [7][8][9], In recent years, many cephalosporin ABs have been developed and clinically used. Cephalosporins also con tain ß-lactam rings, and allergic responses have been ob served after cephalosporin therapy.…”