Development of Screening Method for IgA-Promoting Factors Derived from Food Extracts Using a Human Myeloma Cell Line

IgA is thought to be critical for intestinal immune system. Generally, the effect of food components on intestinal immune system is evaluated by animal experiments. However, the development of simple screening method using human cell culture makes them more cost effective and high-throughput. Thus, we investigated the culture condition of the IgA-producing human myeloma cell line KHM-1B that has unstable culture properties such as cluster formation, resulting in rapid cell death. Considering high-throughput screening, the culture condition was examined in 96-well culture plates and the following parameters were periodically measured: 1. Time to form clusters, 2. Viability, and 3. IgA production. As a result, we obtained a clone which could grow well and produce IgA antibodies stably. The doubling time of this clone was about 72 h, and continuously generated IgA antibodies for 2 months. Then, in order to examine the effect of food components on IgA production using this culture system, various components such as ascorbic acid, raffinose, lactoferrin, fructooligosaccharides, casein tryptic digests, strawberry crude extracts, and IL-6 as a positive control were added to the KHM-1B cell culture medium. The extracts from several kinds of strawberry as well as IL-6 were found to promote IgA production in KHM-1B cells. These results might be useful for screening of food derived IgA-promoting factors.