Proinflammatory activity on rat carotid endothelium of albumins obtained by different procedures

To investigate whether the proinflammatory activity of intravenously administered albumins is related to their preparation method, we compared bovine albumins obtained by alcohol precipitation and by heat shock. This last procedure produced a notable increase in monocyte adhesion/mm2 in rat carotid endothelium (48 +/- 31, n = 32 rats, vs 7 +/- 6, n = 24 rats, mean +/- S.D., P < 0.001). We found no changes in fluorescence emission in these two groups, and no correlation was observed between leukocyte adhesion and the contents of free fatty acids, free -SH groups, fructosamine, dimers and polymers. The inhibition profile of the proinflammatory activity by polyanionic molecules (fucoidan and dextran sulfate 500 kD) was compatible with the recognition of heat-shocked albumins by scavenger receptors. Thiol disulfide exchange in albumins was produced by ageing with cysteine and by incubation with protein disulfide isomerase. Albumins thus modified increased the adhesion of leukocytes to the endothelium, which indicates that some isomeric forms of albumin generated by thiol disulfide exchange may acquire proinflammatory behavior.