Expression of CD64 on polymorphonuclear neutrophils in patients with familial Mediterranean fever

P>Familial Mediterranean fever (FMF) is an autoinflammatory disease characterized by recurrent episodes of fever and serosal or synovial inflammation. We examined the utility of CD64 (Fc gamma RI) expression in polymorphonuclear neutrophils (PMNs) as clinical and biological parameters in patients with FMF. We studied 12 Japanese FMF patients (mean age; 22 center dot 8 +/- 15 center dot 5 years, male/female: 2/10), along with rheumatoid arthritis patients (RA, n = 38 male/female: 6/32, mean age; 52 center dot 2 +/- 15 center dot 3 years), systemic lupus erythematosus (SLE, n = 15 male/female: 0/15, mean age; 38 center dot 5 +/- 15 center dot 9 years) and 12 healthy subjects (male/female: 3/9, mean age; 37 center dot 9 +/- 17 center dot 2 years). CD64 expression on PMNs was determined using flow cytometry. The quantitative expression of CD64 in patients with FMF (2439 center dot 6 +/- 2215 center dot 8 molecules per PMN) was significantly higher than in healthy subjects (547 center dot 8 +/- 229 center dot 5, P = 0 center dot 003) or in patients with RA (606 center dot 5 +/- 228 center dot 2, P < 0 center dot 0001) and SLE (681 center dot 3 +/- 281 center dot 1, P = 0 center dot 004). The increased CD64 expression on PMNs isolated from untreated FMF patients was down-regulated by colchicine treatment. NACHT-LRR-PYD-containing protein 3 (NLRP3) activation using MurNAc-(L)-Ala-(D)-isoGln (MDP) resulted in increased CD64 expression on PMNs from healthy subjects. Our results suggest that quantitative measurement of CD64 expression on PMNs can be a valuable tool to discriminate between FMF and autoimmune diseases.