Immune response of healthy adults to the ingested probiotic Lactobacillus casei Shirota.

Immune response of healthy adults to the ingested probiotic Lactobacillus casei Shirota.

Harbige LS et al. (2016) Scandinavian Journal of Immunology 84(6):353-364

doi: 10.1111/sji.12495

Daily ingestion of a probiotic drink containing Lactobacillus casei Shirota (LcS; 1.3 × 1010 live cells) by healthy adults for (1) 4-week LcS, (2) 6-week discontinuation of LcS and (3) 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 there was 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 weeks 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 reduced CD14+cell pro-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.