Returning to the Wild: Restoring Natural Levels of Immune Function to Laboratory Animals

Aims: The loss of biodiversity from the human body, caused by cultural factors in Western society such as widespread use of sewer systems and water treatment facilities, has resulted in a propensity for aberrant immune function, leading to pandemics of allergy, autoimmunity, and other inflammation-related disorders. One approach to combating this problem is through artificial enrichment of the human biota with microbes or other organisms such as helminths. In this study, the extent to which immune function found in wild caught rats could be recapitulated by enriching the biota of laboratory rats was examined.

Place and Duration of Study: Department of Surgery, Duke University Medical Center, from June 2009 to present.

Methodology: Natural antibody levels against autologous antigen extracts were used as a quantifiable and reproducible marker for immune function, and laboratory rats were immunized to boost their natural antibody levels. Co-housing with wild rodents and colonization with helminths were used as tools for biota enrichment.

Results: Three groups of rats with varying levels of biota composition were evaluated; wild rats (n=8), biota-enriched laboratory rats (n=15) and biota-depleted laboratory rats (n=20). Laboratory rats had approximately 33% of natural IgG and IgM levels compared to wild rodents. Biota enrichment in laboratory animals enhanced levels of natural IgG and IgM to similar extents. Immunization boosted the level to 47%, and co-housing with wild rodents coupled with exposure to helminths boosted the level further to within 72% of levels found in wild rodents.

Conclusion: This study indicates that artificial biota enrichment in laboratory animals can significantly enhance immune function that is known to be important for cancer surveillance, wound healing, and a variety of other immune functions.