In animal research, a clean environment is often considered a mandatory condition to avoid collateral and unwanted stimuli that might interfere with the experimental condition a researcher is investigating. On the other hand, the immune system of these animals seems to remain stunned by the lack of immune challenges, some says, to the point that these animals might not represent a bona fide model for the immune system.
As a matter of fact, immune system constantly struggles against some dirt; could a less pristine environment in animal research be the answer to obtain more rigorous animal models of human immune functions?