Selective effects of Lactobacillus casei Shirota on T cell activation, natural killer cell activity and cytokine production

Modulation of host immunity is an important potential mechanism by which probiotics confer health benefits. This study was designed to investigate the effects of a probiotic strain, Lactobacillus casei Shirota (LcS), on immune function, using human peripheral blood mononuclear cells (PBMC) in vitro. In addition, the role of monocytes in LcS-induced immunity was also explored. LcS promoted natural killer (NK) cell activity and preferentially induced expression of CD69 and CD25 on CD8+ and CD56+ subsets in the absence of any other stimulus. LcS also induced production of IL-1β, IL-6, TNF-α, IL-12 and IL-10 in the absence of lipopolysaccharide (LPS). In the presence of LPS, LcS enhanced IL-1β production, but inhibited LPS-induced IL-10 and IL-6 production, and had no further effect on TNF-α and IL-12 production. Monocyte-depletion significantly reduced the impact of LcS on lymphocyte activation, cytokine production and NK cell activity. In conclusion, LcS preferentially activated cytotoxic lymphocytes in both the innate and specific immune system, which suggests that LcS could potentiate the destruction of infected cells in the body. LcS also induced both pro-inflammatory and anti-inflammatory cytokine production in the absence of LPS, but inhibited LPS-induced cytokine production in some cases. Monocytes play an important role in LcS-induced immunological responses.

Resistance is costly: trade-offs between immunity, fecundity and survival in the pea aphid

Parasitoids are among the most important natural enemies of insects in many environments. Acyrthosiphon pisum, the pea aphid, is a common pest of the leguminous crops in temperate regions. Pea aphids are frequently attacked by a range of endoparasitic wasps, including the common aphidiine, Aphidius ervi. Immunity to parasitoid attack is thought to involve secondary symbiotic bacteria, the presence of which is associated with the death of the parasitoid egg. It has been suggested that there is a fecundity cost of resistance, as individuals carrying the secondary symbionts associated with parasitoid resistance have fewer offspring. Supporting this hypothesis, we find a positive relationship between fecundity and susceptibility to parasitoid attack. There is also a negative relationship between fecundity and off-plant survival time (which positively correlates with resistance to parasitoid attack). Taken together, these results suggest that the aphids can either invest in defence (parasitoid resistance, increased off-plant survival time) or reproduction, and speculate that this may be mediated by changes in the aphids' endosymbiont fauna. Furthermore, there is a positive relationship between aphid size and resistance, suggesting that successful resistance to parasitoid attack may involve physical, as well as physiological, defences.

Humoral immunity following chickenpox is influenced by geography and ethnicity

Objectives To investigate the contribution of ethnicity and geographical location to varicella-zoster virus (VZV) serostatus and antibody concentrations. Methods The presence and concentrations of antibodies to VZV were measured in 639 Bangladeshi women born in Bangladesh (BBB), 94 Bangladeshi women born in the UK (BUK) and 262 White women born in the UK (WUK). The results were anaylsed in relation to demographic and social data. Results BBB women were significantly less likely to be VZV seropositive at all ages than both BUK and WUK women. However, the odds of a Bangladeshi-born woman being seropositive increased by 1.04 for each year under the age of 15 spent in the UK. In contrast, antibody concentrations were significantly lower in ethnic Bangladeshi women, irrespective of country of birth. White, but not Bangladeshi women, showed evidence of antibody boosting over time despite the latter having more exposure to children. Conclusion Geographical location during childhood is the major influence on age of primary infection with VZV while the level of antibody is related to ethnicity. Since the risk of re-infection with VZV following both natural infection and vaccination is increased as antibody concentrations fall, these results have implications for VZV vaccination programmes particularly in non-White populations.