EXPRESSION OF FUNCTIONAL HUMAN RECOMBINANT INTERLEUKIN-12 AND DEVELOPMENT OF A NEW RELIABLE BIOASSAY BY INTERFERON-GAMMA ELISPOT

Interleukin-12 (IL-12) is one of the important cytokines for promoting the differentiation and maturation of type 1 T helper cells and facil itating the initiation of cell-mediated immune responses. Because of i ts multi-functional roles in anti-tumor and anti-viral immunity, IL-12 is considered a promising therapeutic cytokine in immunotherapy again st cancer and infectious diseases. To evaluate the therapeutic efficac y, an easy and reliable quantitative assay for functional IL-12 is ess ential. Presently, IL-12 concentration is often determined by ELISA or RIA, which may or may not correlate with IL-12 biological function. E stablished IL-12 bioassays are based on a time-consuming lymphocyte pr oliferation assay and require freshly isolated peripheral blood lympho cytes. In this report, we demonstrated the production of functional IL -12 by a bi-cistronic eukaryotic expression vector using a simple IL-1 2 bioassay that adapted the IFN-gamma ELISPOT method. In comparison wi th other established methods, this improved IL-12 bioassay is very sen sitive and reproducible, and should be useful for the routine quantita tive IL-12 bioassay.