Release of microparticles (MPs) from blood cells may occur upon various activation signals. MPs from neutrophil and platelet have been studied in systemic infectious diseases and cardiovascular diseases, respectively. They are here investigated in common nephropathies including vasculitis and dialysis, two conditions characterized by neutrophil activation. Flow cytometry analysis of neutrophil-derived (CD66b-positive) and platelet-derived (CD41a-positive) MPs was performed on 213 plasma samples from patients with various nephropathies, including 46 patients with vasculitis and 40 hemodialysis patients. MPs released ex vivo, during neutrophil activation in whole blood, were also measured in these patients. Correlations with clinical parameters and creatinine clearance were evaluated. The results show that MPs present in plasma from patients or healthy controls are from various origins: platelet-derived (38+/-22%), neutrophil-derived (2.8+/-3.8%) MPs, mixed aggregates of neutrophil/platelet MPs (28+/-15%) or neither from neutrophil or platelet (null) 31+/-20%. Acute vasculitis showed the highest level of all types of MPs, while other nephropathies did not result in significant changes of MP levels. A significant increase was observed during hemodialysis sessions. In patients with renal failure, no correlation was seen between MP levels and creatinine clearance. In conclusion, neutrophil and platelet MP levels are non-specific markers of neutrophil activation during vasculitis acute phase and dialysis-induced inflammation. Circulating aggregates of neutrophil/platelet MPs co-express adhesion molecules of both cell types and may be thus endowed with inflammation and coagulation- thus modulating properties.

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Renal amyloidosis has been considered rare and late in the evolution of the transthyretin (TTR) familial amyloid polyneuropathy (FAP) of the Portuguese type (type I). Renal biopsy has been performed systematically in 14 patients with FAP type I before liver transplantation. In all patients, TTR Met30 mutation was shown. Seven had proteinuria or abnormal microalbuminuria, whereas seven others had no urinary abnormalities. All had renal amyloid deposition predominantly in the medulla. Glomerular and vascular involvement was more prominent in patients with urinary abnormalities. Patients with the most extensive renal lesions represented a subgroup with a low score of polyneuropathy disability, a high prevalence of nephropathy in the proband generation, or a late onset for relatives with nephropathy. Immunohistochemistry studies showed that the amyloid substance corresponded to transthyretin. We have shown that renal TTR-derived amyloid deposition is common in patients with FAP type I, even in the absence of urinary abnormalities. The clinical presentation of nephropathy is not a late occurrence in the disease. PMID:9631837 [PubMed -indexed for MEDLINE]http://www.ncbi.nlm.nih.gov/pubmed?term=PMID%3A%209631837%20