RESUMEN
The recent advances in the area of pharmaceutical recombinant DNA products have led to an impressive increase in the number of clinically used therapeutic proteins, for which stringent purity requirements are established by authorities. Nucleic acids are host cell derived contaminants and their allowed level in the final product is in the low pg range, because of the health risk to the patient. Even if fast non-radioactive methods have been recently developed as an alternative to the traditional hybridization assay, the latter is still widely used being a specific and sensitive method. However hybridization quantitative aspects are only partially reviewed in the literature as well as the procedures utilised to cope with the possible interference of the sample protein on the assay results. These topics are described in the present paper by detailing and comparing the methods set up for three recombinant proteins: human pro-Urokinase (r-h-proUK), human basic fibroblast growth factor (r-h-bFGF) and human granulocyte macrophage colony stimulating factor (r-h-GMCSF).