ASPECTS OF PREANALYTICAL VARIATION OF LACTOFERRIN AND ELASTASE ALPHA-1-PROTEASE INHIBITOR COMPLEXES

A number of interesting applications of plasma elastase/al-protease in hibitor complexes (ELA-PI) and lactoferrin (LAC) have recently been su ggested. However, the clinical utility of these components often seems to be low. This might be improved by minimizing the preanalytical var iation, if possible. Therefore, we have evaluated the influence of var ious aspects of sampling and handling conditions on the results obtain ed when measuring ELA-PI and LAC. Blood samples from both healthy pers ons as well as patients, who had undergone laparotomy the day before, were investigated. We confirmed the previous observations of higher co ncentrations of ELA-PI and LAC in serum compared to plasma. This was m ore pronounced in patients than in healthy adults. In EDTA-blood the m ost important change was seen in samples from patients when stored at room temperature. In this situation increases of LAC concentrations of 50% and 100% following 2 and 5 h, respectively were found. This in vi tro release of LAC was abolished when samples were stored on ice until centrifugation within 5 h. In contrast, a statistically significant i ncrease in ELA-PI of 10% was observed following storage on ice for 2h of blood specimens drawn from healthy persons. EDTA-plasma obtained by venous puncture following minimal stasis contained 10% higher concent rations of LAC compared to samples drawn from intravenous catheters, w hile no difference was observed in the case of ELA-PI. However, in one individual prolonged venous stasis resulted in larger differences of both LAC and ELA-PI. Different centrifugation conditions (1500 vs. 300 0 x g; room temperature vs. 4-degrees-C) did not influence concentrati ons of LAC or ELA-PI measured, neither did eating a normal meal nor mo derate physical activity (30 min walk). In conclusion, ELA-PI and LAC should be measured in EDTA-plasma. Blood must be drawn by venous punct ure applying minimal stasis or from indwelling venous catheters. Sampl es for measuring LAC must be stored on ice until centrifugation. Separ ation of plasma from cells should be performed as fast as possible, bu t storage for up to 5 h can be accepted.