QUALITY-CONTROL PROGRAM FOR STORAGE OF BIOLOGICALLY BANKED BLOOD SPECIMENS IN THE MALMO DIET AND CANCER STUDY

A biological bank has been developed to extend the biochemical and mol ecular research base for a prospective study on diet and cancer in the city of Malmo, Sweden. The study entered individuals 45-69 years of a ge, of which 30,382 individuals (45%) participated, Each individual en tering the bank has stored samples of viable mononuclear leukocytes (M NLs; -140 degrees C) and granulocytes (GRANs; -80 degrees C) or buffy coats (-140 degrees C), erythrocytes (-80 degrees C), and plasma/serum (-80 degrees C), The bioassays developed to monitor the quality of st orage conditions were: (a) viability and growth response to phytohemag glutinin for MNLs; (b) DNA strand breakage for GRANs; (c) NAD content for erythrocytes; and (d) thiol status for plasma/serum. The yield, pu rity, and storage conditions were all quality controlled, and the samp les were determined to be of high standard after 137-190 weeks of stor age. No differences in yield and purity were found in samples banked b y different laboratory technicians. Growth responses of MNLs were seve rely reduced (90%) after 40 weeks of storage, which justified switchin g from the storage of purified MNLs and GRANs to the more cost-effecti ve banking of huffy coats. We conclude that the quality of the banked material, based on the biochemical analysis done, indicate that the st orage conditions are optimal at least up to 3.5 years, except for the growth response of MNLs.