Stability of Manually Prepared Test Cells for Blood Grouping
Direct Answer
Manually prepared test cells from known blood groups should be used fresh and stored at refrigerator temperatures (4-10°C) in the dark, with stability limited to approximately 7-14 days maximum, though optimal practice is to prepare them fresh for each testing session.
Storage and Stability Requirements
Immediate Post-Preparation Handling
- All stained samples must be stored immediately in the dark at refrigerator temperatures (4-10°C) until analysis 1.
- Fixation with 1-2% buffered paraformaldehyde or formaldehyde should be performed after preparation, even if commercial reagents contain fixatives 1.
- Paraformaldehyde and formaldehyde characteristics vary from lot to lot and lose effectiveness over time, requiring fresh preparation weekly from electron microscopy-grade aqueous stock 1.
Maximum Stability Periods
- Paper-based blood grouping test cells have demonstrated stability of 7 days at 4°C when properly prepared and stored 2.
- Some modified preparations (e.g., chitosan-modified surfaces) have shown stability ≥100 days at 25°C, though this applies to specialized platforms rather than standard manual preparations 2.
- Standard practice recommends 14-day maximum storage at 4°C for manually prepared test cells 2.
Quality Control Considerations
Control Cell Requirements
- Positive methodologic controls using whole blood specimens from control donors must be prepared each time patient specimens are prepared 1.
- Control cells should match the population of patients being tested in the laboratory 1.
- If controls fall outside established normal ranges, the reason must be determined before proceeding 1.
Testing Reagent Controls
- New lots of reagents must demonstrate similar results to those of known acceptable performance 1.
- Whole blood specimens or other human lymphocyte preparations (cryopreserved or commercially obtained lyophilized lymphocytes or stabilized whole blood) can be used for reagent validation 1.
Critical Preparation Factors Affecting Stability
Sample Preparation Variables
- Include a source of protein (e.g., fetal bovine serum, bovine serum albumin) in wash buffer to reduce cell clumps and autofluorescence 1.
- Maintain centrifugation forces between 300-400g for 3-5 minutes during wash steps 1.
- Vortex sample tubes immediately before analysis to optimally disperse cells 1.
Storage Environment
- All tubes must be incubated and stored in the dark during the entire immunophenotyping procedure 1.
- Temperature control at 4-10°C is mandatory for maintaining cell integrity 1.
Common Pitfalls and Caveats
Factors Compromising Stability
- Patient-related factors such as irregular antibodies against red blood cells can complicate immunohematology diagnostics 3.
- Certain medications (e.g., daratumumab) lead to significantly increased complexity in laboratory analyses 3.
- Massive transfusions can lead to chimerism with more than one population of circulating red blood cells, affecting test cell reliability 3.
Quality Assurance Requirements
- Document all quality assurance activities related to test cell preparation and storage 1.
- Maintain records of preparation dates, storage conditions, and validation testing 1.
- Review and revise laboratory policies at established intervals to ensure adherence to quality assurance programs 1.
Practical Recommendations
Optimal Practice
- Prepare test cells fresh for each testing session whenever possible to eliminate stability concerns 1.
- When storage is necessary, limit to maximum 14 days at 4°C in the dark 2.
- Validate each batch of prepared test cells against known standards before clinical use 1.
Validation Requirements
- Test new preparations in parallel with cells of known acceptable performance 1.
- Ensure accurate and reliable blood group typing through serological testing based on hemagglutination reactions 4.
- Consider emerging technologies for blood group testing as alternative approaches when serological methods cannot determine blood groups 4.