Mechanism of graft-versus-host-induced lymphadenopathy in mice. Trapping vs. proliferation.

Graft-vs.-host (GVH)-induced lymphadenopathy of the popliteal lymph node has been produced in C57BL/6 x A/J F(1) (BAF(1)) mice by injecting A/J spleen cells into the rear footpads. By giving (51)Cr-labeled BAF(1) lymphoid cells intravenously to the hosts, 24 h before sacrifice, we have demonstrated that a large portion of the GVH-induced lymphadenopathy is due to the trapping of circuating lymphocytes in the challenged lymph nodes. Most of the remaining enlargement can be attributed to proliferation of host cells within the reacting lymph nodes. Conditions have been defined under which the weights and [(14)C]thymidine incorporation of the popliteal nodes can be plotted against the dose of injected A/J spleen cells on a double-log scale to give a linear dose-response. The popliteal lymph node GVH assay is a simple and effective means of quantitating immune reactivity to histocompatibility antigens in mice.