| Summary: | L-leucyl-L-leucine methyl ester (LLME) is known to remove lysosome-rich cells from human
peripheral blood mononuclear cells (PBMCs). To evaluate the immunopotentiating ability of
lactic acid bacteria (LAB), we adopted the in vitro stimulation protocol of LLME-treated
PBMCs as a model assay system and monitored the level of antibody produced by stimulated
PBMCs. The results indicated that several LAB strains have immunopotentiating ability
against PBMCs, as evidenced by the enhanced antibody production and increased number of
antigen-specific B cells. Next, we identified T cells as the direct target cells of the
immunopotentiating LAB strain L32, suggesting that L32 induced antibody production by
PBMCs through T-cell activation. Finally, we tested the immunopotentiating ability of
ligands for Toll-like receptor 2 (TLR2), which is known to mediate the LAB signal, and
observed that both L32 and one of the TLR2 ligands, LTA-BS, induced antigen-specific
antibody production by in vitro stimulated PBMC. This suggests that L32 and LTA-BS can be
used as an adjuvant for stimulating immune reaction in PBMCs.
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