Enhanced recovery of gut-associated lymphoid tissue by infusion of buffy coat cells and gut leukocytes in the murine syngeneic bone marrow transplantation model

Ways of accelerating recovery of the mucous membrane immune system in lethally irradiated mice following syngeneic bone marrow transplantation were studied over a 35-day period by quantification of jejunal intraepithelial lymphocytes (IELs) and lamina propria plasma cells. Recovery after a low bone marrow dose allowing 100% animal survival (LBM) was compared with a high (five times minimal) dose (HBM), or a minimal dose augmented with equal numbers of buffy coat cells (LBM + BC) or small gut mucosal lymphocytes (LBM + GL). The maximal decline and subsequent peak repopulation of IELs were: LBM, days 7 through 14, peaking suboptimally by day 28; HBM, day 14, peaking suboptimally but higher than LBM by day 35; LBM + BC, days 11 through 14, peaking at control levels by day 35; and LBM + GL, day 7, peaking at control levels by day 28. The IEL decline was most severe with LBM and HBM treatment and least with LBM + GL. All transplant groups experienced maximal plasma cell decline by day 7. LBM had the most severe depletion, and LBM + GL had the least. Recovery to control levels for the LBM, HBM, LBM + BC and LBM + GL groups occurred by days 28, 21, 21, and 14, respectively. In all instances, greater than 95% of the plasma cells were IgA positive.