Determination of ANA specificity using the UltraPlex platform.

SmartBead Technologies has developed a multiplexed immunofluorescence assay, the UltraPlex ANA Profile, which determines nine antinuclear antibodies simultaneously. The UltraPlex assay platform uses bar-coded microparticles to track analytes through assays. These bar-coded microparticles were used to tag and track key ANA markers: Jo-1, Scl-70, Sm, SmRNP, SSA, SSB, U1RNP, Centromere B, dsDNA, and a blank control microparticle. The immunofluorescence assays are fully automated and are performed on a Perkin-Elmer multiprobe II liquid handling system that performs all sera dilutions, additions of reagents, washes, and incubation steps. Results were determined by the automated UltraPlex plate reader. This fully automated multiplex antinuclear antibody (ANA) immunoassay was used to screen commercially available ANA-positive sera and negative control samples. The UltraPlex ANA Profile enables the panels of samples to be screened simultaneously for nine ANA antoantibodies, requiring significantly less labor and fewer reagents, with performance equivalent to existing gold-standard methods.

Association study of candidate genes for the prevalence and progression of knee osteoarthritis.

OBJECTIVE: Osteoarthritis (OA), characterized by late-onset degeneration of articular cartilage, is recognized to have a genetic component. We examined the role of 26 single-nucleotide polymorphisms (SNPs) from 24 candidate genes in OA susceptibility and progression. METHODS: We compared human complementary DNA libraries from OA-affected and normal cartilage and synovium and selected 22 genes in addition to the estrogen receptor alpha and vitamin D receptor genes. Based on the availability of polymorphisms, we proceeded to test whether genetic variation at those genes affected susceptibility to or progression of radiographic knee OA over a 10-year period in 749 women (mean age 64 years) from the longitudinal Chingford Study. RESULTS: After adjusting for age and body mass index, we observed significant associations at ADAM12, BMP2, CD36, COX2, and NCOR2 with 3 OA susceptibility traits (presence/absence of joint space narrowing [JSN], presence/absence of osteophytes, and Kellgren/Lawrence [K/L] score). For the OA progression traits (change over 10 years in the K/L score, osteophyte grade, and JSN grade), we found significant associations with ADAM12, CILP, OPG, and TNA. Overall, we observed 15 associations with nominal significance (P < 0.05) and, by permutation analysis, found that such a number would be observed by chance only 3.8% of the time. Although these tests require replication, the stronger genetic associations observed are unlikely to be attributable simply to multiple comparisons. CONCLUSION: Our results suggest that OA severity and progression have a multigenic and feature-specific nature. These findings should encourage the development of genetic diagnostics for OA progression based on multiple SNPs and help unravel some of the complex disease mechanisms in OA.