ANALYTICAL ASPECTS REGARDING THE MEASUREMENT OF METALLOPROTEINASES AND THEIR INHIBITORS IN BLOOD

Objective: Both in vitro and in vivo investigations have shown that th e balance between matrix metalloproteinases (MMP) and the tissue inhib itors of metalloproteinases (TIMP) seems to be important in physiologi cal and pathological processes which involve tissue remodeling and rep air. Design and Methods: In order to investigate the analytical reliab ility of new commercial ELISA tests, BIOTRAK(TM) test kits (Amersham I nt.) were used for the determination of metalloproteinase-1 (MMP-1), t issue inhibitor of metalloproteinase-1 (TIMP-1), and the MMP-1/TIMP-1 complex in blood. Results: The detection limits and the precision data were in the usual ranges of ELISA tests so that concentrations found in blood could be determined reliably. Since all three analytes were l ower in heparin plasma than in serum or EDTA plasma, heparin plasma wa s selected as the specimen of choice. Measurement of diluted samples g ave higher values than those of undiluted native plasma samples becaus e the inhibitory effects of specific/unspecific inhibitors or other ma trix components were apparently reduced. To obtain comparable data fro m different laboratories, the predilution of samples must be defined. We recommend to use diluted plasma samples of 1:5, 1:21, and 1:11 for the determination of MMP-1, TIMP-1, and the complex MMP-1/TIMP-1, resp ectively. The preliminary upper 95% reference limits measured under th ese conditions in healthy subjects (40 females. 40 males) were 14.4 mu g/L for MMP-1 in females, 20 mu g/L for MMP-1 in males, 1668 mu g/L f or TIMP-1 and 116 mu g/L for the complex MMP-1/TIMP-1. Conclusion: The study has shown that the BIOTRAK(TM) test combinations for MMP-1, TIM P-1, and MMP-1/TIMP-1 complex allow a reliable measurement of the anal yte concentrations in heparin plasma. In order to avoid preanalytical misinterpretations only heparin plasma samples in defined dilutions sh ould be used.