Biol. Pharm. Bull. 30(11) 2163—2166 (2007)

industrially important microorganisms used for the production of various fermented foods. Recently, probiotic lactic acid bacteria defined as “living microorganisms that benefit the health of the host by conditioning the intestinal environment” have attracted the attention of many scientists, and began to be applied in the dairy industry. For example, the intake of fermented milk containing probiotic lactic acid bacteria is known to improve the balance of the intestinal microflora by both increasing beneficial bacteria and reducing harmful bacteria in the intestine. Moreover, the immunomodulating effects of lactic acid bacteria have also been reported and some specific strains of lactic acid bacteria are recognized to alleviate allergic diseases such as allergic rhinitis. Although the etiology of allergic disease is still unclear, disturbance of the intestinal microflora, especially endogenous lactic acid bacteria, has been regarded as one of the important reasons related to allergic diseases. Accordingly, improvement of the intestinal environment by the intake of probiotic lactic acid bacteria is considered effective for modulation of the immune system. Lactobacillus acidophilus strain L-55, which was originally isolated from healthy infant feces, is probiotic lactic acid bacteria used as a starter strain for the fermentation of dairy products. Strain L-55 possesses adherent ability to Caco-2 cells derived from the human enteric epithelium; therefore, it may be capable of regulating the immune system. The purpose of the present study was to examine the inhibitory effect of oral administration of strain L-55 on experimental allergic rhinitis in BALB/c mice.