TABLE 1.

Effects of suboptimal storage temperature and temperature cycling on IFN-γ ELISPOT responses during storagea

Storage condition and stimulating agentAvg no. of SFC/106 PBMCFold difference95% CIP
Controlb
    VZV antigen351
    EPI peptide pool302
    PHA mitogen2,492
Suboptimal storage tempc
    VZV antigen749.331.4-77.4<0.001
    EPI peptide pool1126.415.8-44.2<0.001
    PHA mitogen11222.312.5-39.9<0.001
Storage temp cyclingd
    VZV antigen3108.669.2-170.3<0.0001
    EPI peptide pool2214.08.4-23.4<0.0001
    PHA mitogen4086.13.4-10.9<0.0001
  • a A total of 100 frozen aliquots of PBMC from each of two donors (M3143 and M5020) were tested. Results were combined across both donor PBMC samples. The analysis for individual donors was consistent with the pooled analysis. One assay run testing aliquots for donor M3143 was lost; so, for this donor, the results for analysis were reduced to 15 aliquots for the control and 34 aliquots each for suboptimal storage temperature and temperature cycling during storage.

  • b A total of 20 aliquots from each donor were maintained in LN2 storage.

  • c A total of 40 aliquots from each donor were subjected to an 8-h period of storage at −20°C and then returned to LN2 storage.

  • d A total of 40 aliquots from each donor were subjected to three cycles of storage change between LN2 to −70°C and back to LN2.