Abstract
Commensal bacteria in the intestine play an important role in the development of immune response. These bacteria interact with cells of the gut-associated lymphoid tissues (GALT). Among cells of the GALT, B-1 cells are of note. These cells are involved in the production of natural antibodies. In the present study, we determined whether manipulation of the intestinal microbiota by administration of probiotics, which we had previously shown to enhance specific systemic antibody response, could affect the development of natural antibodies in the intestines and sera of chickens. Our findings demonstrate that when 1-day-old chicks were treated with probiotics, serum and intestinal antibodies reactive to tetanus toxoid (TT) and Clostridium perfringens alpha-toxin in addition to intestinal immunoglobulin A (IgA) reactive to bovine serum albumin (BSA) were increased in unimmunized chickens. Moreover, IgG antibodies reactive to TT were increased in the intestines of probiotic-treated chickens compared to those of untreated controls. In serum, IgG and IgM reactive to TT and alpha-toxin were increased in probiotic-treated, unimmunized chickens compared to levels in untreated controls. However, no significant difference in serum levels of IgM or IgG response to BSA was observed. These results are suggestive of the induction of natural antibodies in probiotic-treated, unimmunized chickens. Elucidating the role of these antibodies in maintenance of the chicken immune system homeostasis and immune response to pathogens requires further investigation.