title: IV immunoglobulin confounds JC virus antibody serostatus determination.
abstract: OBJECTIVE
  To determine the impact of therapeutic infusion of IV immunoglobulin (IVIg) on John Cunningham virus antibody (JCV Ab) serostatus and level in serum.
  
  
  METHODS
  We carried out a retrospective analysis of serum levels of JCV Ab among STRATIFY-2 trial enrollees from 2 multiple sclerosis centers who were exposed to IVIg during the trial. For the subset of eligible patients, we estimated mean linear trends while on IVIg and after stopping IVIg with a linear mixed-effects model.
  
  
  RESULTS
  The JCV Ab seropositivity rate in the group of patients that was recently exposed to IVIg was 100%, which is significantly higher than in the IVIg-naive population (58%, p < 0.001). The seropositivity rate in the patient group with remote IVIg exposure was similar to that in the IVIg-naive population (67%, p = 0.68, Fisher exact test). The slope of the linear trend line after stopping IVIg decreased significantly by -0.310 units per 100 days (95% confidence interval, -0.611 to -0.008; p = 0.04).
  
  
  CONCLUSIONS
  Recent IVIg exposure is invariably associated with JCV Ab seropositivity. After stopping IVIg, JCV Ab levels tend to decrease with time, and seroreversion to innately Ab-negative status can occur.
authors.affiliation: NYU Multiple Sclerosis Care Center (I.K., M.O., J.H.), Department of Neurology, NYU School of Medicine, New York, NY; Barnabas Multiple Sclerosis Care Center (I.K., M.Y., J.H.), Department of Medicine, Barnabas Medical Center, Livingston, NJ; Biogen Idec (G.K., M.S.), Cambridge, MA; Department of Epidemiology (E.C.), University of Alabama at Birmingham School of Public Health, Birmingham, AL; and Specialized Clinical Services (K.D.), Park Ridge, NJ.
authors.forename: Ilya
authors.initials: I
authors.lastname: Kister
authors.affiliation: NYU Multiple Sclerosis Care Center (I.K., M.O., J.H.), Department of Neurology, NYU School of Medicine, New York, NY; Barnabas Multiple Sclerosis Care Center (I.K., M.Y., J.H.), Department of Medicine, Barnabas Medical Center, Livingston, NJ; Biogen Idec (G.K., M.S.), Cambridge, MA; Department of Epidemiology (E.C.), University of Alabama at Birmingham School of Public Health, Birmingham, AL; and Specialized Clinical Services (K.D.), Park Ridge, NJ.
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Kuesters
authors.affiliation: NYU Multiple Sclerosis Care Center (I.K., M.O., J.H.), Department of Neurology, NYU School of Medicine, New York, NY; Barnabas Multiple Sclerosis Care Center (I.K., M.Y., J.H.), Department of Medicine, Barnabas Medical Center, Livingston, NJ; Biogen Idec (G.K., M.S.), Cambridge, MA; Department of Epidemiology (E.C.), University of Alabama at Birmingham School of Public Health, Birmingham, AL; and Specialized Clinical Services (K.D.), Park Ridge, NJ.
authors.forename: Eric
authors.initials: E
authors.lastname: Chamot
authors.affiliation: NYU Multiple Sclerosis Care Center (I.K., M.O., J.H.), Department of Neurology, NYU School of Medicine, New York, NY; Barnabas Multiple Sclerosis Care Center (I.K., M.Y., J.H.), Department of Medicine, Barnabas Medical Center, Livingston, NJ; Biogen Idec (G.K., M.S.), Cambridge, MA; Department of Epidemiology (E.C.), University of Alabama at Birmingham School of Public Health, Birmingham, AL; and Specialized Clinical Services (K.D.), Park Ridge, NJ.
authors.forename: Mirza
authors.initials: M
authors.lastname: Omari
authors.affiliation: NYU Multiple Sclerosis Care Center (I.K., M.O., J.H.), Department of Neurology, NYU School of Medicine, New York, NY; Barnabas Multiple Sclerosis Care Center (I.K., M.Y., J.H.), Department of Medicine, Barnabas Medical Center, Livingston, NJ; Biogen Idec (G.K., M.S.), Cambridge, MA; Department of Epidemiology (E.C.), University of Alabama at Birmingham School of Public Health, Birmingham, AL; and Specialized Clinical Services (K.D.), Park Ridge, NJ.
authors.forename: Kim
authors.initials: K
authors.lastname: Dontas
authors.affiliation: NYU Multiple Sclerosis Care Center (I.K., M.O., J.H.), Department of Neurology, NYU School of Medicine, New York, NY; Barnabas Multiple Sclerosis Care Center (I.K., M.Y., J.H.), Department of Medicine, Barnabas Medical Center, Livingston, NJ; Biogen Idec (G.K., M.S.), Cambridge, MA; Department of Epidemiology (E.C.), University of Alabama at Birmingham School of Public Health, Birmingham, AL; and Specialized Clinical Services (K.D.), Park Ridge, NJ.
authors.forename: Mary
authors.initials: M
authors.lastname: Yarussi
authors.affiliation: NYU Multiple Sclerosis Care Center (I.K., M.O., J.H.), Department of Neurology, NYU School of Medicine, New York, NY; Barnabas Multiple Sclerosis Care Center (I.K., M.Y., J.H.), Department of Medicine, Barnabas Medical Center, Livingston, NJ; Biogen Idec (G.K., M.S.), Cambridge, MA; Department of Epidemiology (E.C.), University of Alabama at Birmingham School of Public Health, Birmingham, AL; and Specialized Clinical Services (K.D.), Park Ridge, NJ.
authors.forename: Meena
authors.initials: M
authors.lastname: Subramanyam
authors.affiliation: NYU Multiple Sclerosis Care Center (I.K., M.O., J.H.), Department of Neurology, NYU School of Medicine, New York, NY; Barnabas Multiple Sclerosis Care Center (I.K., M.Y., J.H.), Department of Medicine, Barnabas Medical Center, Livingston, NJ; Biogen Idec (G.K., M.S.), Cambridge, MA; Department of Epidemiology (E.C.), University of Alabama at Birmingham School of Public Health, Birmingham, AL; and Specialized Clinical Services (K.D.), Park Ridge, NJ.
authors.forename: Joseph
authors.initials: J
authors.lastname: Herbert