Levamisole and graft-versus-host reaction (GvHR) in rats

The influence of levamisole on local GvHR was studied. The drug injected at doses of 10 mg/kg or at 2.5 mg/kg of body weight into rats was found to stimulate GvHR. The intensity of the reaction was measured by the popliteal lymph node (PLN) enlargement, the number of cells contained in the node and by [3H]-thymidine incorporation into those cells. The values of all of these parameters were enhanced when the PLN was analyzed between 5-7 days of GvHR. Levamisole influenced the kinetics of GvHR by increasing its intensity, causing its earlier initiation and prolonging its duration. The drug incubated for 30 min with donor lymphocytes, which then elicited the reaction, had little but reproducible effect on the development of the reaction. The optimal schedule of levamisole administration has been determined. This drug was found to be the most effective when given after the GvHR initiation. Levamisole caused the induction of GvHR when suboptimal doses of donor lymphocytes were injected.