Tamm–Horsfall protein isolated from urine of pregnant and non-pregnant women has similar oligosaccharides

Background Differences in the immunosuppressive activity of Tamm–Horsfall protein and uromodulin claimed by many investigators are controversial. They have been ascribed to variations in the carbohydrate moiety. Methods We isolated urinary glycoproteins from 18 non-pregnant (THP) and 12 pregnant (UM) women using the same method (adsorption on diatomaceous earth) and performed comparative studies including monocarbohydrate analysis and tests of reactivity with lectins, cytokines and serum proteins. Results No significant differences in monocarbohydrate content or in the reactivity with specific lectins were found between the native urinary glycoproteins or between their proteolytic products. Also, in Sda+ and Sda− donors monitored throughout pregnancy and after delivery, no time-dependent differences in the sugar moiety were observed. We found that THP/UM from Sda+ donors reacted more strongly with PHA-L than THP/UM from Sda− donors, providing further evidence for carbohydrate variations between Sda+ and Sda− determinants. No differences between THP and UM in terms of their reactivity with recombitant human interleukin (rhIL) 1α, recombinant human tumour necrosis factor (rhTNF) α and some serum proteins were found, indicating similar biological activity. Conclusion The results of our carbohydrate analysis together with previous data on amino acid analysis indicate that Tamm–Horsfall protein and uromodulin are identical or very similar glycoproteins.