Intravenous immunoglobulin (IVIG) is made from large pools of blood donors. Some patients may have antibodies to various infectious agents that are in a titer high enough to be detectable after dilution.
Presentation:
(1) The patient has received a large amount of IVIG.
(2) The patient tests positive for antibodies after receipt of the IVIG.
(3) Testing of other vials from the same lot of IVIG show the same antibody.
It is recommended that testing for antibodies be done prior to IVIG therapy or 3 months later (length of time IgG antibodies circulate).
The differential diagnosis is a true positive. An infection related to contaminated IVIG would initially generate IgM antibodies, and IgG antibodies would probably be present 3 months or more after the IVIG infusion. Antibodies related to an infection acquired prior to the IVIG might not persist, so it is important to look for associated antibodies that might be persistent.
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