Probiotic effects on T-cell maturation in infants during weaning

We previously reported that feeding the probiotic Lactobacillus paracasei ssp. paracasei F19 (LF19) during weaning reduced the cumulative incidence of eczema.

To investigate the impact of feeding LF19 on T-cell maturation.

One hundred and seventy-nine healthy, term infants with no prior allergic manifestations were randomized to daily intake of cereals with (n = 89) or without (n = 90) the addition of LF19 10(8 ) colony forming units per serving from 4 to 13 months of age. Venous blood was drawn at 5.5 and 13 months of age. We used the cytokine response to polyclonal T-cell stimulation by anti-CD3 plus anti-CD28 monoclonal antibodies, and in vitro stimulation with the vaccine tetanus toxoid (TT) as measures of global adaptive immunity and capacity to raise a specific T-cell response, respectively. Expression levels of IL-2, IFN-γ, IL-4, IL-17A and IL-10 messenger RNAs (mRNAs) were used as proxies for general T-cell stimulation and naive Th0 cells, Th1-, Th2-, Th17- and T regulatory lineages.

There was no difference between the two groups at 5.5 months of age. At 13 months, the polyclonal IL-2 response was higher in the placebo group (P < 0.05), whereas the IFN-γ/IL-2 (P < 0.01) and IL-17A/IL-2 (P < 0.05) ratios after polyclonal stimulation were higher in the probiotic group, as was the TT-specific IL17-A response (P < 0.001). In both groups, the IFN-γ and IL-4 responses increased from 5.5 to 13 months upon both polyclonal and specific stimulation (P < 0.01), whereas the IL-10 response remained low (P > 0.05).

Our findings suggest modest effects by probiotics on T-cell maturation following 9 months of probiotic intake. Future studies should address if specific probiotics may drive immune development with possible preventive effects on the development of allergic disease.