Assessment of a Line Immunoassay for the Detection of Mi-2 Antibodies: Results From a Single Academic Center Investigation.

OBJECTIVES: To evaluate the performance characteristics of a line immunoassay (LIA) for the detection of Mi-2 antibodies associated with dermatomyositis (DM). METHODS: In total, 432 consecutive patient specimens were tested for Mi-2 antibodies concurrently by LIA (Mi-2α or Mi-2ß) or immunoprecipitation (IP) test and antinuclear antibody by indirect immunofluorescence assay using HEp-2 substrate. Following antibody evaluation, results for patients positive in any of the assays for Mi-2 antibody had a retrospective chart review for diagnostic categorization. The performance of all tests was evaluated based on the extracted clinical data. RESULTS: Forty patients were positive in at least one of the Mi-2 assays. The frequency of Mi-2ß antibody by LIA was highest (75.0%), followed by Mi-2 by IP (35.0%) and Mi-2α by LIA (20.0%), respectively. Mi-2 by IP had the best total percent agreement for DM (95.0%) compared with 70.0% and 25.0% for the LIA Mi-2α and Mi-2ß, respectively. Positivity of the Mi-2ß antibody was significantly associated with non-DM diagnosis. CONCLUSIONS: Agreement for DM with assays for detecting Mi-2 is variable. Additional studies are required to validate Mi-2 immunoassays for routine patient evaluation.

Population-Wide Associations between Common Viral Pathogens and Self-Reported Arthritis: NHANES 2009-2012.

OBJECTIVE: Persistent infectious agents have been implicated in chronic and recurrent inflammation, which may trigger or worsen many types of arthritis. Our objective was to determine whether exposure to herpes simplex virus (HSV) and human papillomavirus (HPV) is associated with self-reported arthritis among US adults. METHODS: We used data from two consecutive cycles of the National Health and Nutrition Examination Survey (NHANES) from 2009 until 2012 (N of examined adults ages 20-69 = 9483). Participants were classified as having arthritis by self-report. Viral serology for HSV-1 and HSV-2 and HPV PCR studies from oral rinse and vaginal swabs were available for analysis. We compared HSV-1 and HSV-2 seropositivity as well as oral and vaginal HPV DNA positivity between participants with self-reported arthritis vs. those without, adjusting for age, gender, race, income, education, BMI, and the use of immunosuppressive medications. We used three comparator outcomes, gout, kidney stones, and hypertension, to evaluate whether the associations were specific or not to arthritis. RESULTS: Arthritis was associated with older age, female gender, non-Hispanic White and Non-Hispanic Black race, higher BMI, and lower socioeconomic status. HSV-2 seropositivity, but not HSV-1 seropositivity, was independently associated with arthritis after adjustment for age, gender, race, income, education, BMI, and the use of immunosuppressive medications: AOR 1.48 (1.10-1.99). Oral HPV DNA positivity was also independently associated with arthritis: AOR 1.63 (1.17-2.28). After adjustment, there was no statistically significant difference in vaginal HPV DNA positivity between those with vs. those without arthritis: AOR 1.22 (0.90-1.66). There were no significant associations between viral exposures and any of the comparator outcomes. CONCLUSIONS: HSV-2 seropositivity and oral HPV DNA positivity were associated with self-reported arthritis and not with comparator outcomes, after adjustment for multiple potential confounders. These findings should be confirmed in longitudinal studies.