Probiotics are a live microbial supplement that reside within the intestinal tract and are considered normal flora. The Balb/c mouse model was used to determine if the elimination of probiotics, general LAB species, by antibiotics plays a role in the breakdown of oral tolerance leading to the generation of an immune response to oral antigens. A mouse model was developed for in vivo research regarding probiotic populations and the effect on the induction of oral tolerance. The Balb/c mouse was used to determine if the mouse model had a colonized intestinal tract with probiotics followed by a reduction of probiotics that was done with orally administered antibiotics. After the reduction of probiotics, mice were fed oral antigen, ovalbumin, to determine that an immune response was not shown with oral antigen alone. After the mouse model was set up, mice were then fed oral antigen and then stimulated with immunizations to study the induction of oral tolerance and the possible effect of the absence of probiotics. The results indicated that mice with reduced probiotics and fed with oral antigen alone do not show an immune response. In contrast, mice fed with oral antigen followed by immunization indicate a higher OVA-specific serum IgG. This is evidence that correlates with clinical findings in disease states such as Crohn's Disease and Irritable Bowel Syndrome (IBD). / Department of Biology