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Abstract

The enhancement of protein concentration by Ültracentrifugation using microconcentrators (Centricon 10, Fa. Amicon) can facilitate the measurement of enzyme-activities in bronchoalveolar lavage fluid (BALF). The elastase inhibition capacity (EIC) was quantified using an enzyme assay with the specific chromogenic substrat Meo-Suc-Ala-Ala-Pfo-Val-p-Nitroanilid. The concentration of ajPi was measured by chemiluminescence immuno assay. Ültracentrifugation increased the sensitivity of the EIC assay from W mlU/ml to 0.3 mlU/ml. The intraassay-variation was 5.24 %. The variation in the series was 5.45 %. The recovery for EIC and <* 7 P/ was about 93%, the recovery for elastase activity about 52 %. The functional activity ofa-iPi (ElC/ ^ ) In BALF of 21 patients with acute pneumonia, of 9 patients after successful treatment of pneumonia and of W healthy persons was determined. Elastase-activity resp. EIC was detected in 26 of 30 BALF of the pneumonia patients and in 9 of 10 BALF of the healthy persons. Measurement in native BALF showed activity only in 2 of the pneumonia patients and none of the healthy persons. The mean functional activity ofajPi in BALF of patients with acute pneumonia (0.63 [+/-0,75] n^l(J/ g) was significantly lower than in BALF of patients after treatment (3.98 [+/-4.05] mlUfag) and BALF of healthy persons (7.61 [+/-3.35] mlUfag; p = 0). The functional activity was inversely proportional to the granulocytosis in the lavage. Ültracentrifugation of BALF is an practical and precise method to increase the sensitivity of enzyme assays.