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Determination of Macrolipase in a Patient with Waldenström's Macroglobulinemia by Karl Raab, Egon Werle, Markus Zorn, Walter Fiehn

An 81-year-old female patient suffering from Waldenström's macroglobulinemia lgM-kappa displayed normal amylase activity and a lipase activity eight times that of the upper reference limit. Precipitation with Polyethylene gfycol (PEG) resulted in a 77.4% loss of lipase activity in the supernatant, which is suspicious for a macrolipase. Lipase actitvity and - partially - IgM concentration were determined in plasma fractionated by size-exclusion chromatography. Peak lipase activity in the exclusion fraction (apparent molecular mass >600.000 Da) proved the presence of a macrolipase. Agarose electrophoresis of the exclusion fraction followed by immunofixation electrophoresis revealed IgM, kappa light chains, and lipase activity at the same zones. This indicates the presence of a macrolipase IgM-kappa. One may speculate that the monoclonal IgM-kappa type was reactive with the lipase
molecule, thus forming this type 1 macroenzyme complex.

DOI: Clin. Lab.1999;45:7-11