Immune Reactivity in Dogs With Spontaneous Malignancy

The humoral and cellular immune reactivity and reticuloendothelial system (RES) clearance in 62 dogs with malignant lymphoma (L) or lymphoblastic leukemia and 35 with solid, nonhematologic tumors (ST) were studied before treatment. The IgG levels were significantly low in dogs with L but not in those with ST. Hemagglutinin titers after sheep red blood cell immunization were suppressed in dogs with L and normal in those with ST. Findings were similar after primary and secondary immunization with bacteriophage. Both groups of animals developed Iymphocytotoxic antibodies after allogeneic skin grafts from unrelated dogs. Cellular immunity, assessed by first- and second-set allogeneic skin-graft survival, was impaired in dogs with L but not in those with ST. Response to tuberculin challenge after sensitization with BCG and in vitro lymphocyte blastogenesis after stimulation by phytohemagglutinin or allogeneic lymphocytes was deficient in both groups of dogs. RES function, assessed by clearance of bacteriophage from the circulation, was impaired in dogs with L and normalin those with ST. These results demonstrated that dogs with L had a marked deficiency of immunologic and RES function. Dogs with ST were intact with regard to humoral immunity and RES function, but had a partial deficit in cellular immune reactivity. These findings in untreated dogs are important in the elucidation of host-tumor interactions and in the design and evaluation of therapeutic approaches to the treatment of malignant disease.