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

Abstract

Studies evaluating long-term trends of intravenous immunoglobulin (IVIG) titers against microorganisms such as bacteria and fungi have not been conducted. We herein evaluated long-term trends of titers of IVIG lots manufactured from 1998 to 2018, derived from donors in Japan, against microorganisms affecting patients with primary or secondary immunodeficiency diseases. Titers against four strains of Pseudomonas aeruginosa, three strains of Staphylococcus aureus, four strains of Haemophilus influenzae, two strains of Klebsiella pneumoniae, one strain of Streptococcus pneumoniae, Enterococcus faecium, Bordetella pertussis, Serratia marcescens, and Candida albicans, were tested immediately after lot release in a commercial clinical testing facility in 1998. The long-term (whole period) and short-term (first and second half of the period) trends of titers were evaluated using regression analysis. The IVIG lots indicated meaningful titers against all microorganisms that were stable in the short term. The long-term trends could be categorized into stable, slightly decreasing, or decreasing trends, except for the metallo-β-lactamase-producing K. pneumoniae, which indicated a slight increase. Notably, three strains of P. aeruginosa showed remarkable decreasing long-term trends in the titer. 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.