RESUMEN
The use of antibodies in immunodiagnostic kits generally implies the conjugation of these proteins with other molecules such as chromophores or fluorochromes. The development of more sensitive quality control procedures than spectrophotometry is essential to assure the use of better fluorescent conjugates since the fluorescent conjugates are critical reagents for a variety of immunodiagnostic kits. In this article, we demonstrate a new flow cytometric protocol to evaluate conjugates by molecules of equivalent soluble fluorochromes (MESF) and by traditional flow cytometric analysis. We have coupled microspheres with anti-IgG-PE and anti-HBSAg-PE conjugates from distinct manufactures and/or different lots and evaluated by flow cytometry. Their fluorescence intensities were followed for a period of 18 months. Our results showed that there was a great difference in the fluorescence intensities between the conjugates studied. The differences were observed between manufactures and lots from both anti-IgG-PE and anti-HBSAg-PE conjugates. Coefficients of variation (CVs) showed that this parameter can be used to determine better coupling conditions, such as homogenous coupling. The MESF analysis, as well as geometric mean evaluation by traditional flow cytometry, showed a decrease in the values for all conjugates during the study and were indispensable tools to validate the results of stability tests. Our data demonstrated the feasibility of the flow cytometric method as a standard quality control of immunoassay kits.
Asunto(s)
Anticuerpos Inmovilizados/química , Citometría de Flujo/métodos , Colorantes Fluorescentes/química , Inmunoensayo/métodos , Inmunoconjugados/química , Animales , Anticuerpos Antiidiotipos/química , Anticuerpos Antiidiotipos/inmunología , Anticuerpos Inmovilizados/inmunología , Anticuerpos Monoclonales/química , Anticuerpos Monoclonales/inmunología , Fluoresceína-5-Isotiocianato/química , Fluorescencia , Antígenos de Superficie de la Hepatitis B/inmunología , Humanos , Inmunoconjugados/inmunología , Inmunoglobulina G/inmunología , Microesferas , Ficoeritrina/química , Control de CalidadRESUMEN
Purification of recombinant hepatitis B surface antigen (recHBsAg) produced in a stable Chinese hamster ovary (CHO) cell line was evaluated using Linx Affinity Purification System (Invitrogen, USA). To purify HBsAg secreted by this cell line, a murine monoclonal antibody (MAbAH1) raised against native HBsAg was used. The purified AH1MAb was conjugated with phenyldiboronic acid (PDBA) and immobilized on the immunoaffinity chromatographic support. Using an optimized protocol the affinity column was able to purify recHBsAg from supernatant of mammalian cells cultures with more than 80% purity. This method showed to be simple and quicker than the current ultracentrifugation methods. The method is also efficient and economical in obtaining purified recHBsAg.