IV IG making false positives for JC Virus

Kister I, Kuesters G, Chamot E, Omari M, Dontas K, Yarussi M, Subramanyam M, Herbert J. IV immunoglobulin confounds JC virus antibody serostatus determination. Neurol Neuroimmunol Neuroinflamm. 2014 Sep 18;1(3):e29. doi: 10.1212/NXI.0000000000000029. eCollection 2014 Oct.

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.


Intravenous immunoglobulin is a the antibodies from a large pool  of over a thousand people and if you get this for your MS, then it gives you the potential for a false positive anti-JC virus test,

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