Monthly hemagglutination reactions for positive and negative QC cells
| Month 1 | Month 2 | Month 3 | Month 4 | |
|---|---|---|---|---|
| Positive control | 4+ | 4+ | 4+ | NP* |
| Negative control | 0 | 0 | 0 | 0 |
Abbreviations: NP, not performed.
*T-activated positive QC cells were hemolyzed during the fourth month of testing, so a 3%–5% cell suspension could not be made.