Experimental Study on Prevention of GVHD by Selective Elimination of Alloreactive Donor Lymphocytes Prior to Stem Cell Transplantation.

Objective: To investigate a new concept aiming for induction of graft-vs-leukemia (GVL) effect prior to stem cell transplantation (SCT). Mismatched lymphocytes given pre-SCT will be followed by selective elimination of alloreactive donor lymphocytes, thus avoiding lethal graft-vs-host disease (GVHD).

Methods: Female (BALB/c×C57BL/6)F1 mice (H-2^d/b) as recipients received sublethal total body irradiation (TBI) of 4 Gy (⁶⁰Coγ-ray) on day 0 followed by being inoculated with 0.5×10⁷ P388D1 leukemia cell line on day 1, injection of 1.5×10⁷ allogeneic splenocytes supplied by C57BL/6 male mice(H-2^b)for induction of GVHD, intraperitoneally injection of cyclophosphamide (Cy) (200 mg/kg) or TBI (9 Gy) were given on day 7, one day later, treated mice were rescued with 3×10⁷ syngeneic bone marrow cells supplied by (BALB/c×C57BL/6)F1 male mice(H-2^d/b). Recipients were observed clinical manifestation, phenotype, re-establishment of haematogenesis, histopathologic changes of internal organs suffered from GVHD and investigated donor chimerism by the semi-quantitate analyses of polymerase chain reaction (PCR). Data was analyzed by SPSS 10.0 software and expressed as mean ± SD.

Results: Recipients had no occurrence of leukemia and GVHD by selective elimination of alloreactive donor lymphocytes by Cy and TBI, survived more than 210 days, to become complete-donor chimerism on day +21. The ratio of chimerism descended subsequently, but still displayed mixed-chimerism on day +90. Control mice died of evident GVHD, leukemia or other death-related-transplantation within 20 to 36 days(p<0.01). Attempting to induce GVL effects by mismatched lymphocytes given before stem cell transplantation followed by selective elimination of alloreactive donor lymphocytes, thus avoiding graft-vs-host disease (GVHD) was feasible.