Augmentation of cytokine production and mucosal immunity in gut-associated lymphoid tissue by the probiotics.

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The Lactobacillus acidophilus group, a member of gastrointestinal lactic acid bacteria (LAB) widely used in dairy foods, is expected to develop as a probiotic LAB because of the ability to stimulate host immune responses. We have evaluated and assessed the mitogenic responses of the LAB to lymphocytes as an incidence of biological activity among them. The present study was conducted to determine the mitogenic factors from the LAB, particularly focusing on mitogenic DNAs in the LAB.In 12 of 16 strains of Lactobacillus acidophilus group LAB, the DNA components significantly stimulated mitogenic responses to murine splenocytes. The mitogenic activity to lymphocytes from peyer's patches, a gut-associated lymphoid tissue, was also observed in some DNAs. The active DNA (DNA1131) of Lactobacillus gasseri JCM1131^T was selected to analyze the active components. Plasmid DNAs from the positive clones obtained by suctioning, using the pUG119 vector ligated with 1131DNA partially digested with Sau … More 3Al, were purified by the precipitation method with polyethylene glycol. The plasmid DNA templates were amplified by using the polymerase chain reaction (POR) with primers for the multicloning site of the vector. In the 108 of the 321 positive colonies significant mitogenic activity was detected. The active nucleotides which stimulated mitogenic response were sequenced by a DNA sequencer MODEL 4000(Ll-COR, Lincoln, USA). Ten high homologous DNA motifs were found in the active DNA, but not in the non-active DNA.Two DNA motifs of chemically synthesized the DNA motifs induced a mitogenic response and was characterized as a B-cell specific mitogen. The binding of the active DNA clone and motifs to B lymphocytes were demonstrated by scatchard analysis and laser nicroscopy. The active DNA clone and motif augmented CD69/86 induction on B lymphocytes of spleen and peyer's patches. These also augmented induction of cytokine (IFNa. IFNy, TNRx) mRNA in splenocytes and peyer's patches. These findings indicated that a novel DNA motifs inducing lymphocyte activation triggering mitogenic response and , different from CpG motifs from E coli recently reported as a B-cell mitogen, exists in DNAs from L.Gasseri. Less