IMMUNOSUPPRESSIVE EFFECTS OF CHLOROQUINE - POTENTIAL EFFECTIVENESS FOR TREATMENT OF POSTTRANSFUSION GRAFT-VERSUS-HOST DISEASE

Post-transfusion graft-versus-host disease (PT-GVHD) is a fatal advers e effect of blood transfusion. In spite of its severity, there is no e ffective treatment at present for PT-GVHD. Previously, we reported tha t chloroquine (CH) inhibited the cytotoxicity of cytotoxic T-cell (CTL ) clones and tumour necrosis factor beta (TNF beta) production by TNF beta-producing clones in vitro, both the clones being derived from per ipheral blood lymphocytes (PBMCs) of PT-GVHD patients. To explore the possibility of utilizing CH for the treatment of PT-GVHD, we extended our investigation of the immunosuppressive effects of CH in vitro to P BMCs derived from healthy donors. Our results show that CH inhibits th e mixed lymphocyte reaction (MLR) between allogeneic PBMCs, production of inflammatory cytokines such as TNF alpha, interleukin-1 beta (IL-1 beta) and interferon gamma (IFN gamma) in mixed lymphocyte culture an d natural killer cell activity, and, further, reduces the number of al loreactive CTL precursors.