Quantitation of serum phospholipase A2 by enzyme-diffusion in lecithin agar gels. A comparative study in man and animals.

A sensitive gel-diffusion assay for determination of phospholipase A was developed. PLA standards, serum, faecal and pancreas homogenate samples with PLA-activity were allowed to diffuse from wells into agar-gels containing lecithin-membranes. The turbidity cleared radially upon PLA-activity. The diameters of the cleared zones showed a linear relationship with the log of the enzyme concentration. Serum samples resulted in some turbidity within the cleared zones. This interference originating from serum lipoproteins could be abolished by hydrophobic absorption. The gel-diffusion method was compared with two other methods for PLA, titrimetric and radiometric techniques. Analysis on 37 human patients with acute pancreatitis showed close interrelationship between these methods. The phospholipase A activity in sera from man, the dog, the horse, the cow, the pig and the cat were almost equal, but much less than in the albino rat. No significant differences between PLA activities in pancreatic samples were obtained in different animal species. Of the faecal samples, the cow had the lowest PLA activity. Dogs suffering from pancreatic degenerative atrophy (PDA), had significantly reduced PLA activity both in their pancreas and faeces but not in serum.