The cryopreservation of standard sera

Area of Science:

• Immunology
• Serology
• Biochemistry

Background:

• Standardized sera are crucial for reliable serodiagnostic test results.
• Optimal storage conditions are necessary to maintain serum integrity over time.
• Previous studies have not definitively established the ideal long-term storage temperature for diverse serodiagnostic assays.

Purpose of the Study:

• To evaluate the efficacy of different storage temperatures (-70°C and -20°C) for preserving standard sera used in serodiagnostic tests.
• To determine the optimal storage temperature based on the specific requirements of various serodiagnostic assays.
• To assess the long-term stability of sera stored for up to five years.

Main Methods:

• Groups of standard sera were stored at -70°C and -20°C for up to five years.
• Sera were tested for stability and performance before and after storage.
• Comparative analysis of serum integrity and test results across different storage conditions and time points.

Main Results:

• Serum preservation effectiveness varied depending on the specific serodiagnostic test.
• Storage at -70°C showed no significant advantage over -20°C for immunofluorescence assays.
• Complement fixation tests demonstrated inadequacy at -70°C, performing significantly worse than storage in liquid nitrogen.

Conclusions:

• The optimal storage temperature for standard sera is assay-dependent.
• -70°C storage offers marginal benefits over -20°C for some serodiagnostic tests but is insufficient for complement fixation.
• Liquid nitrogen remains superior for complement fixation, while -20°C may suffice for immunofluorescence and other specific assays.