Much important and interesting immunology occurs across different barriers in the body. The gastrointestinal mucosa provides niches that microbes can colonise and an extensive associated lymphoreticular system that interfaces with this external environment, monitoring and maintaining it against invasive pathogens. Interactions with toxins produced by bacteria, with commensal organisms and with pathogenic, meningitis causing bacteria, are all studied be researchers who are part of this group.
At the other end of the spectrum is the blood retinal barrier that preserves ocular immune privilege. The function of this barrier changes radically under inflammatory conditions, such as arise in uveitis. This inflammation can be controlled by treatment but patients show heterogeneity in their responses and this is studied particularly with regard to sensitivity to steroids.