We examined the inhibitory effect of the extract of kakrol extracted by 3 types of solvent (water, 50% and 100% ethanol) on histamine release in human basophilic KU812 cells. The water extract of kakrol flesh showed the strongest inhibitory effect on histamine release as compared with the other extracts. Therefore, we evaluated whether water extract of kakrol flesh had a suppressive effect on development of atopic dermatitis-like lesions in picryl chloride-treated NC/Nga mice. The dietary kakrol flesh water extract alleviated the development of skin lesions in ears accompanied by lower IgE levels and inflammatory cytokines levels in serum. These results indicate that the water extract of kakrol flesh might have therapeutic potential for allergic responses in vitro and in vivo.
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.