Studies on Homotransplantable Lymphomas in Hamsters

Further experiments with two homotransplantable lymphomas are reported. Previously, it was demonstrated that each tumor provoked a different morphological response in the recipients' lymphoid tissues. One of the lymphomas, which metastasizes widely, was found to stimulate marked plasmacytosis in the draining nodes; the other, which does not metastasize, induced a massive proliferation of sinus histiocytes and interfollicular blast cells. In the present work, immunofluorescent staining in tissues from hamsters bearing subcutaneous grafts of the two tumors has been compared, using a conjugated rabbit anti-hamster γ-globulin serum. The metastasizing tumor stimulates a marked increase in specifically stained lymphoid cells in the medullary cords of the draining nodes and in the spleen; most of the tumor cells themselves are also coated with γ-globulin. The nonmetastasizing lymphoma evokes a different response with a small increase in stained cells in the regional nodes, moderately increased staining in the spleen, but no staining of the tumor cells. These observations provide further evidence for the view that the metastasizing lymphoma initiates a predominantly humoral immune response. The nonmetastasizing lymphoma is associated with a more complex reaction: cellular mechanisms predominate but humoral components, principally derived from the spleen, are also involved, which may be specific enhancing antibodies. General implications are considered.