Pattern of Cytokine Responses to Gram-Positive and Gram-Negative Commensal Bacteria is Profoundly Changed when Monocytes Differentiate into Dendritic Cells

Lactobacilli are nonpathogenic gram-positive inhabitants of the normal human intestine known for their health-promoting effects. In our earlier work, it is shown that human monoclonal antibody isolated from sera of a patient with Waldenstrom macroglobulinaemia possess innate antibody characteristics and binds to lactic acid bacteria. According to the immune network model, immunization with this bacteria could induce the perturbations in immune system that might result in production of anti-Lactobacillus antibodies, human monoclonal antibody like (Ab1) and anti-idiotypic antibody (Ab2). In this study, BALB/ c mice were immunized with two doses of bacteria Lactobacillus acidophilus in complete and incomplete Freund's adjuvant and phosphate-buffered saline (PBS), respectively. Seven days after the last immunization, sera from immunized mice were collected and the presence of Lactobacillus-specific Ab1 and Ab2 were determined by ELISAs. In the sera of immunized mice, antibodies specific to bacteria Lactobacillus acidophilus were shown. The concentration of Lactobacillus-specific antibodies was higher in the sera of hyperimmunized mice (mice immunized with 1 mg of IgM DJ) than in sera of mice immunized with 100 times lower doses of immunogen (0.01 mg per doses). Moreover, Ab1 and Ab2 antibodies were detected in the sera of Lactobacillus-hyperimmunized mice. In this study, we have shown the idiotypic network interactions in mice immunized with bacteria Lactobacillus acidophilus .