This zip archive contains the chromatography data that was used to calculate the values displayed in Table S3. “WT_USI_raw_data.xlsx” contains the data for the wild-type upper small intestine, “Rag1KO_USI_raw_data.xlsx” contains the data for the immunoglobulin-deficient (Rag1KO) upper small intestine. In both the excel files, RI = refractive index, RALS = Right-angle light scattering, LALS = low-angle light scattering, DP = differential pressure (the viscometer). All values are measured in millivolts except for retention volume, which is measured in milliliters (mL). The file “Table S3 – source data 1.OmnisecArchive” contains all this data, along with the data for the pullulan and dextran standard that were used to calibrate the instrument. This can be used in conjunction with Malvern OMNISEC v10.20 software to reproduce the calculations displayed in the table. LALS data was not used for these calculations because of the noisiness of the signal from the detector.