Development of quality control preparations for immunocytochemical assessment of urokinase-type plasminogen activator

Quality control of immunochemical and/or immunocytochemical analyses warran ts constant reproducibility and reliability of assay performance. In this r espect, stable reference preparations containing known quantities of the co mponents to be assessed may serve purposes in the quality assessment of ant igen expression levels, including those of the plasminogen activation syste m. Quality control preparations for the immunocytochemical assessment of ur okinase-type plasminogen activator (uPA) were developed using different com binations of cultured cell lines (BLM and IF6), each expressing immunochemi cally well-defined (by enzyme-linked immunosorbent assay[ELISA]) amounts of the respective component. Cytospins and frozen sections cut from sucrose/T issue-Tek blocks containing these cell lines demonstrated stable and homoge neous expression of uPA. An excellent correlation was found between the imm unocytochemical staining results and the data obtained by ELISA. Because th ese cell lines are available in practically unlimited quantities, large num bers of nearly identical quality control preparations can be made over a lo ng period of time. Therefore, the incorporation of (combinations of) cell l ines in cytospins or sucrose/Tissue-Tek blocks represents a simple model sy stem in establishing quality control preparations for immunocytochemical as sessment of components of the plasminogen activator system.