CYTOKINE MESSENGER-RNA AND PROTEIN EXPRESSION IN A MIXED LEUKOCYTE REACTION BEFORE AND AFTER ALLOGENEIC TRANSFUSIONS

Background. The precise mechanism by which pretransplant blood transfu sions may favorably influence the graft outcome in human transplantati on remains unknown. Here, we explored whether the mechanism might be r elated to an alteration of cytokine response to transplantation antige ns. Methods. Eight patients awaiting kidney transplantation were selec ted to receive a single planned pretransplant blood transfusion. Befor e transfusion and 7 days after transfusion, peripheral blood mononucle ar cells from these patients were isolated and in vitro stimulated in a one-way mixed leukocyte reaction (MLR) by using allogeneic fixed Eps tein Barr virus-transformed cells as stimulators. Results. The use of a semiquantitative reverse-transcriptase polymerase chain reaction cyc le technique to analyze cytokine mRNAs revealed that allostimulation b y donor cells clearly induced accumulation of interleukin (IL)-2, IL-4 , interferon (IFN)-gamma, and IL-10 mRNA in peripheral blood mononucle ar cells collected both before and after transfusion (eight of eight p atients). However, both T helper 1 (IFN-gamma) and T helper 2 (IL-4) c ytokine responses were more elevated after transfusion in eight of eig ht patients, as were IL-2 responses in five of eight patients. Such up -regulation of cytokine responses by transfusion was mostly directed a gainst blood donor cells. Indeed, after stimulation by third-party cel ls, this up-regulation was both inconstant (two of three patients) and of less intensity, and no change was detected after stimulation by au tologous cells (three of three patients). Conclusions. That IL-2, IL-4 , and IFN-gamma responses to donor cells were increased by transfusion was further supported by results on cytokine secretion showing increa sed levels of IL-2 (P<0.05), IFN-gamma (P=0.054), and IL-4 (P<0.05) pr oteins in supernatants of posttransfusion MLR as compared with pretran sfusion MLR. In contrast, transfusion-induced changes in the amount of IL-10 mRNAs were not obvious and were quite variable from one patient to another.