Graft barriers sustain luminal infection

Some epithelial grafts may let an infection linger in the lumen, the hollow space inside a tissue lining, even while immune surveillance remains active on the tissue-facing side. This proposed mechanism says the barrier may deliver too little neutralizing activity, immune defenses that block a pathogen, from the bloodstream into that lumen. The test holds systemic antibody exposure equal, then delivers the same neutralizing activity directly into the lumen. Faster clearance would support a delivery problem if abnormal-clone killing remains unchanged. Persistence despite adequate luminal concentrations would rule out this transport explanation.