Seroreactivity of patients with Crohn's disease with lymph nodes of primed nude mice is independent of the tissue used for priming.

Athymic nude mice, injected with a cell-free filtrate of intestinal tissue from patients with Crohn's disease, have been shown to express antigens in their lymph nodes to which sera from patients with Crohn's disease contain antibodies. In the present study, immune reactivity was assessed with a histochemical indirect immunoperoxidase assay on paraplast-embedded tissue sections. The reactive lymph node cells were identified as sinus macrophages. We confirmed earlier findings of immunofluorescence studies that the reaction showed some antibody specificity, the proportion of patients with Crohn's disease who were positive (84%) being higher than of patients with ulcerative colitis (29%). However, reactivity of Crohn's disease sera was found to be antigen nonspecific, as it was equally observed with lymph nodes of mice primed with saline or with homogenates from patients with ulcerative colitis, diverticulitis, or volvulus. Hence, this nude mouse model does not seem appropriate to identify a transmissible etiology of Crohn's disease.