[Importance of monoclonal antibodies in the analysis of tumor markers].
Due to their extreme specificity, monoclonal antibodies (Mabs) have been very useful for new analytical progresses in the field of tumor markers. For example, it has been possible to analyse only calcitonin, independently of its precursors in the patients with medullary thyroid carcinomas. These precursors have been estimated and found increased in the absence of calcitonin for many cancer patients, specially with small cell lung tumors. The assay of HCG and its subunits with a great specificity and sensitivity is an other interesting example of the analytical power of Mabs. The usefulness of the assay of beta subunit is now clear in the diagnostic and follow up of choriocarcinoma and perhaps in the screening of high risk pregnancies. An other example can be derivated of our works on neuropeptide Y (NPY). The assay of NPY is highly difficult, due to its great similarity with other neuropeptides (PYY and PP). Mabs have been used to solve these analytical problems. The assay of NPY is useful not only for patients with neuroendocrine tumors, but also experimentally in the rat hypothalamus for research in nutrition.