Storage and stability of IgG and IgM monoclonal antibodies dried on filter paper and utility in Neisseria meningitidis serotyping by Dot-blot ELISA

Aline S Ferraz,Ana P Oliveira,Monica Cg Scola,André Y Yto,Elza Ft Belo,Tatiane Ferreira,Marta Sf Machado,Andréia Ms Carmo,Ligia Mcc Coutinho,Daniele L Franco,Elizabeth De Gaspari

doi:10.1186/1471-2334-8-30

Abstract

BackgroundA simple filter paper method was developed for, the transport and storage of monoclonal antibodies (Mabs) at room temperature or -20°C after spotting on filter paper, for subsequent serotyping of outer membrane antigens of N.meningitidis by dot-blot ELISA.MethodsMonoclonal antibodies (Mabs) were spotted within a 0.5–1 cm diameter area of Whatman grade 903 paper, which were stored individually at room temperature or at -20°C. These MAbs were stored and analyzed after periods of one week, 4 weeks, 12 months, or 13 years in the case of frozen Mab aliquots, or after 4 weeks at -20°C or at room temperature (RT) in the case of Mabs dried on filter paper strips. Assays were performed in parallel using dot-blot ELISA. In addition to the MAbs specific for serotyping class 1, 2 or 3, we used a larger number of Mabs for polysaccharides, lipooligosaccharides (LOS), class 5 and cross-reactive antigens for native outer membrane of N.meningitidis. The Mabs dried on filter paper were eluted with phosphate-buffered saline (PBS) containing 0.2% gelatin.ResultsMabs of the isotypes IgG and IgM dried on filter papers were not affected by duration of storage. The detection by serotyping Mabs was generally consistent for dried filter paper MAb samples stored frozen for over 1 year at -20°C, and although decreased reactive antibody titers were found after storage, this did not interfere with the specificity of the Mabs used after 13 years as dry spots on filter paper.ConclusionThe use of filter paper is an inexpensive and convenient method for collecting, storing, and transporting Mab samples for serotyping studies. In addition, the samples occupy little space and can be readily transported without freezing. The efficiency of using immunoglobulin G (IgG) or M (IgM) eluted was found to be consistent with measurement of IgG or IgM titers in most corresponding, ascites Mabs stored frozen for over 1 year. The application of meningococcal typing methods and designations depend on the question being asked.

Highlights

A simple filter paper method was developed for, the transport and storage of monoclonal antibodies (Mabs) at room temperature or -20°C after spotting on filter paper, for subsequent serotyping of outer membrane antigens of N.meningitidis by dot-blot ELISA
The results of the serological tests performed with ascites or culture supernatant samples and dried Mab spots on paper kept at -20°C or at room temperature are presented in Tables 1, 2, 3, 4
The titers were mostly equal and the differences did not alter the final results when the dried Mab spots were stored at -20°C or at room temperature for a period of one year

Summary

Introduction

A simple filter paper method was developed for, the transport and storage of monoclonal antibodies (Mabs) at room temperature or -20°C after spotting on filter paper, for subsequent serotyping of outer membrane antigens of N.meningitidis by dot-blot ELISA. In 1988, the incidence of MD in the greater Sao Paulo area exceeded 4.06 per 100,000 inhabitants, suggesting a new epidemic in that region. This epidemic differed from previous ones because it was caused by serogroup B strains in 1988 and 1989 and serogroup B and C strains in 1990. The incidence of MD caused by Neisseria meningitidis serogroup C in greater São Paulo has been low since the end of the epidemic situation in 1971 and 1972. In greater São Paulo, there has been a constant increase in the incidence of serogroup C meningococcal disease since the late 1980s [3,4]

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Discussion

Conclusion