Simple determination of donor/host origin and donor leukocyte subsets in rat-mouse chimeras.

In lethally irradiated mice, mixed lymphohaemopoietic chimerism can be established after their reconstitution with adult or embryonic rat haemopoietic stem cells. In this report we describe a simple fluorescent staining protocol for the determination of origin and type of various leukocyte cell subpopulations (rat or mouse, and rat T, B and myeloid cells, respectively) using whole blood samples from such animals. These data were comparable to those obtained in peripheral lymphoid tissues. Exploiting the slightly heterogeneous reactivity of the mouse monoclonal anti-rat CD45 antibody (MRC OX-1) revealed by the application of a PE-labelled monoclonal anti-mouse IgG1 secondary reagent together with a FITC-labelled rat anti-mouse CD45 mAb (IBL-5/25), we could determine the donor-derived T, B and myeloid cells from one sample in a two-step procedure. Further advantages to this easy staining procedure are that PBLs as test cells are readily available and the typing can be repeated, thus offering the opportunity for continuous monitoring of the degree of chimerism.