Long-term monitoring of antibody titers against microorganisms in human intravenous immunoglobulin lots derived from healthy donors in Japan manufactured during 1998-2018.

Some titers indicate decreasing trends against microorganisms over the long-term, however, is not clear whether the phenomenon diminishes the performance of IVIG. The titers of the IVIG lots could provide helpful information to optimize replacement therapy, such as considering trough values based on the titers in the patient plasma. Therefore, continuous monitoring of IVIG titers against microorganisms is important to understand titer fluctuation and epidemiological background.