Human intestinal cell isolation

Intestinal biopsies were obtained with endoscopic biopsy forceps from the rectum and collected in a conical tube with Hanks’ balanced salt solution (HBSS; Corning). Intestinal biopsies were transferred into freezing buffer [10% (v/v) DMSO, 40% (v/v) complete RPMI, and 50% (v/v) FBS] and stored at −80°C. Biopsies were recovered, incubated in HBSS on a shaker, then incubated twice in HBSS and 5 mM dithiothreitol (Thermo Fisher Scientific) with shaking, and then washed in HBSS. Intestinal biopsies were mechanically dissociated, then placed into 10 ml of digestion mixture [complete RPMI, collagenase type VIII (1.5 mg/ml) (Sigma-Aldrich), and deoxyribonuclease I (50 μg/ml) (Roche)] on a rocker at 37°C for 20 min, filtered, and stained with anti-human CD45. CD45⁺ immune cells were sorted on a FACSAria II using the gating strategy shown in fig. S1A.