9.5.3 The preparation should be stored in a refrigerator at 2°C. However, 
short-term storage at up to 37°C has no detrimental effect on the 
activity of the IL2 or units storage stability. The preparation should be 
warmed to room temperature prior to use. 
9.5.4 Repeat freezing and thawing out reduces the activity of the IL2. 
9.5.5 Broken ampoules should be used immediately. 
9.5.6 nIL2 is inactivated at pH values above 10 and below 2. 
9.5.7 All surface contact with glass or plastic results in nIL2 losses. By way 
of example, a tuberculin syringe absorbs about 10% of the given 
activity of the nIL2. 
9.5.8 Sterile filters absorb nIL2. Slight losses occur in the even of filters 
with low protein absorption being used, e.g. Durapore filters from 
Millipore or Gelman sterile filters. The filters should be coated with 
a protein solution - e.g. serum or 0.1% HSA - prior to use. 
9.5.9 Dilutions below 10 5 U/ml cause considerable IL2 loss. This can be 
avoided by introducing into the filuent (phosphate butter solution) as 
a stabilizing agent 0.1% human serum albumin. 
Absolutely essential: introduce the human serum albumin into the 
phosphate buffer solution first, shake, and only then add the nIL2. 
9.5.10 Avoid oxidation losses. 
10.0 PATIENT ELIGIBILITY 
10.1 Patients aged between 1 and 18 years at diagnosis with acute nonlymphocytic 
leukemia in first remission are eligible for this protocol. 
10.2 Patient exclusion includes patients with: 
1. HLA-matched, MLC-compatible donor (unless parents and/or patient 
refuses allogeneic transplant) 
2. life expectancy limited by disease other than leukemia 
3. significant cardiac disease (echo shortening fraction <25%orMUGA 
scan <50%) 
Recombinant DNA Research, Volume 17 
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