Increased phospholipase A activities in sera of intensive-care patients show sn-2 specificity but no acyl-chain selectivity

• Published in: Clinical chemistry (Baltimore, Md.) Vol. 39; no. 5; pp. 782 - 788
• Main Authors: Puttmann, M, Aufenanger, J, von Ochsenstein, E, Durholt, S, van Ackern, K, Harenberg, J, Hoffmann, GE
• Format: Journal Article
• Language: English
• Published: Washington, DC Am Assoc Clin Chem 01.05.1993; American Association for Clinical Chemistry
• Subjects: Adult; Aged; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Biological and medical sciences; Chromatography, High Pressure Liquid; Critical Care; Duodenum - enzymology; Emergency and intensive postoperative care (general aspects). Pathophysiology of surgery; Fatty Acids - analysis; Fatty Acids - metabolism; Female; Glycine max; Heparin - pharmacology; Humans; Intensive care medicine; Male; Medical sciences; Middle Aged; Palmitic Acid; Palmitic Acids - metabolism; Phosphatidylcholines - analysis; Phosphatidylcholines - metabolism; Phospholipases A - analysis; Phospholipases A - blood; Phospholipases A1; Phospholipases A2; Phospholipids - analysis; Phospholipids - metabolism; Reference Values; Substrate Specificity; Human; Intensive care; Lecithin; Pathophysiology; Enzyme; Isozyme; Phospholipase A; Assay; Acute phase protein; Enzymatic activity; Substrate specificity; Serum; Heparin; Resuscitation
• ISSN: 0009-9147; 1530-8561
• DOI: 10.1093/clinchem/39.5.782

Phospholipase A (PLA) activities were measured by high-performance liquid chromatography in two enzyme preparations purified from human duodenal juice and a serum pool as well as in 52 sera from 31 intensive-care patients with various diseases. On the basis of a position-specific fatty acid analysis of the natural substrate ("soybean lecithin") from a commercial PLA kit, serum activities of PLA1 could be clearly distinguished from those of PLA2, which is not possible in the usual measurements made with single-label radioactive substrates. Independent of the type of disease, all sera with highly increased PLA activities (40-200 U/L) showed nearly pure PLA2 characteristics without any preference among oleic, linoleic, and linolenic acid in the sn-2 position of the glycerophospholipid substrate. Nevertheless, very low PLA1 activities (< or = 5 U/L, most likely due to heparin perfusion therapy) could also be detected by palmitic and stearic acid release from the sn-1 position, leading to small changes in fatty acid release patterns of sera with low PLA activities. Measurements with sera from heparin-treated volunteers demonstrated that heparin therapy may initially contribute as much as 22 U/L to increased PLA1 activities but is not important under prolonged therapy. The absence of selectivity with respect to acyl-chain desaturation supports the concept of serum PLA2 as an acute-phase protein rather than a regulator of the arachidonic acid cascade.