Immune Response of Healthy Adults to the Ingested Probiotic Lactobacillus casei Shirota

Daily ingestion of a probiotic drink containing Lactobacillus casei Shirota (LcS; 1.3 x 10(10) live cells) by healthy adults for (i) 4-weeks LcS, (ii) 6-weeks discontinuation of LcS, and (iii) a final 4-weeks of LcS, was investigated. There was a significant increase in expression of the T-cell activation marker CD3(+) CD69(+) in ex vivo unstimulated blood cells at weeks 10 and 14 and a significant increase in the NK cell marker CD3(+) CD16/56(+) in ex vivo unstimulated blood cells at weeks 4, 10 and 14. Expression of the NK cell activation marker CD16/56(+) CD69(+) in ex vivo unstimulated blood cells was 62% higher at week 10 and 74% higher at week 14. Intracellular staining of IL-4 in ex vivo unstimulated and PMA/ionomycin-stimulated CD3(+) β7(+) integrin blood cells was significantly lower at week 10 and 14. Intracellular staining of IL-12 in ex vivo unstimulated and LPS-stimulated CD14(+) blood cells was significantly lower at weeks 4, 10 and 14. Intracellular staining of TNF-α in LPS-stimulated CD14(+) blood cells was significantly lower at weeks 4, 10 and 14. Mucosal salivary IFN-γ, IgA1 and IgA2 concentrations were significantly higher at week 14 but LcS did not affect systemic circulating influenza A-specific IgA or IgG and tetanus specific IgG antibody levels. In addition to the decrease in CD3(+) β7(+) integrin cell IL-4 and a CD14(+) cell anti-inflammatory cytokine profile, at week 14 increased expression of activation markers on circulating T cells and NK cells and higher mucosal salivary IgA1 and IgA2 concentration indicated a secondary boosting effect of LcS. This article is protected by copyright. All rights reserved.