Evaluation of the immune benefits of two probiotic strains Bifidobacterium animalis ssp lactis, BB-12® and Lactobacillus paracasei ssp paracasei, L. casei 431® in an influenza vaccination model: a randomised, double-blind, placebo-controlled study

The present study investigated the ability of Bifidobacterium animalis ssp. lactis (BB-12 (R)) and Lactobacillus paracasei ssp. paracasei (L. casei 431 (R)) to modulate the immune system using a vaccination model in healthy subjects. A randomised, double-blind, placebo-controlled, parallel-group study was conducted in 211 subjects (56% females, mean age 33.2 (SD 13.1) years). Subjects consumed a minimum of 10(9) colony-forming units of BB-12 (R) (capsule) or L. casei 431 (R) (dairy drink) or a matching placebo once daily for 6 weeks. After 2 weeks, a seasonal influenza vaccination was given. Plasma and saliva samples were collected at baseline and after 6 weeks for the analysis of antibodies, cytokines and innate immune parameters. Changes from baseline in vaccine-specific plasma IgG, IgG1 and IgG3 were significantly greater in both probiotic groups v. the corresponding placebo group (L. casei 431 (R), P=0.01 for IgG; P < 0.001 for remaining comparisons). The number of subjects obtaining a substantial increase in specific IgG (defined as >= 2-fold above baseline) was significantly greater in both probiotic groups v. placebo (BB-12 (R), P < 0.001 for IgG, IgG1 and IgG3; L. casei 431 (R), P < 0.001 for IgG1 and IgG3). Significantly greater mean fold increases for vaccine-specific secretory IgA in saliva were observed in both probiotic groups v. placebo (BB-12 (R), P=0.017; L. casei 431 (R), P=0.035). Similar results were observed for total antibody concentrations. No differences were found for plasma cytokines or innate immune parameters. Data herein show that supplementation with BB-12 (R) or L. casei 431 (R) may be an effective means to improve immune function by augmenting systemic and mucosal immune responses to challenge.