A RADIOIMMUNOASSAY FOR THE QUANTIFICATION OF HUMAN UBIQUITIN IN BIOLOGICAL-FLUIDS - APPLICATION TO PARASITIC AND ALLERGIC DISEASES

Purified ubiquitin has been shown to share similar biological and phys icochemical properties with a previously characterized lymphokine, pla telet activity suppressive lymphokine (PASL). This lymphokine, which i nhibits the cytotoxic function of activated platelets, is produced dur ing schistosomiasis and Hymenoptera venom hypersensitivity (HVH). We h ave developed a radioimmunoassay specific for ubiquitin, in order to d etermine the ubiquitin levels in human sera and plasma from patients w ith these pathologies. The working range of the assay was between 60 a nd 500 ng/ml, and the sensitivity was 8-10 ng/ml. The reproducibility, specificity and accuracy were determined under standard condition (PB S-0.3% BSA) and using different biological fluids (human serum, plasma and T lymphocyte supernatant). Using this assay, we found that the ub iquitin concentrations were higher in both schistosomiasis and HVH (up to 150-300 ng/ml) compared with sera and plasma from healthy donors w here the ubiquitin levels did not exceed 50 ng/ml.