Modulation of antibody-mediated immune response by probiotics in chickens.

Probiotic bacteria, including Lactobacillus acidophilus and Bifidobacterium bifidum, have been shown to enhance antibody responses in mammals. The objective of this study was to examine the effects of a probiotic product containing the above bacteria in addition to Streptococcus faecalis on the induction of the chicken antibody response to various antigens, both systemically and in the gut. The birds received probiotics via oral gavage and subsequently were immunized with sheep red blood cells (SRBC) and bovine serum albumin (BSA) to evaluate antibody responses in serum or with tetanus toxoid (TT) to measure the mucosal antibody response in gut contents. Control groups received phosphate-buffered saline. Overall, BSA and SRBC induced a detectable antibody response as early as week 1 postimmunization (p.i.), which lasted until week 3 p.i. Probiotic-treated birds had significantly (P <or= 0.001) more serum antibody (predominantly immunoglobulin M [IgM]) to SRBC than the birds that were not treated with probiotics. However, treatment with probiotics did not enhance the serum IgM and IgG antibody responses to BSA. Immunization with TT resulted in the presence of specific IgA and IgG antibody responses in the gut. Again, treatment with probiotics did not change the level or duration of the antibody response in the gut. In conclusion, probiotics enhance the systemic antibody response to some antigens in chickens, but it remains to be seen whether probiotics have an effect on the generation of the mucosal antibody response.