Gut derived lactic acid bacteria induce strain specific CD4(+) T cell responses in human PBMC.

Background & Aims: Probiotic bacteria are used as food supplement in many different disease settings. The immune modulating capacity of different strains is not always properly tested which might result in a suboptimal choice of strains for clinical use.

Methods: The CD4 T cell responses to 19 different gut derived lactic acid bacteria were tested with different methods to show their diversity in immune modulation and to make a well-founded choice on which strains to use in future clinical trials. After co-culture of PBMC with bacteria, the induction of CD4(+) T cell subsets (regulatory T cells, T helper type (TH)1, TH2 and TH17) was analysed by rtPCR of transcription factor mRNA, intracellular FACS staining of transcription factors and cytokine production.

Results: Bacterial strains all have diverse, unique immune modulatory properties. Strains can induce Treg, TH1, TH2 and TH17 cells which can be shown at different levels of T cell activation, and is consistent for most strains tested. For TH1, TH17 and Treg, a positive correlation between the different methods was found. For TH2 cells the correlation was less consistent.

Conclusions: Probiotic bacteria have very different immune modulating capacities. Analysis of transcription factor mRNA is a suitable method for in vitro characterization of strains prior to clinical application.