Immunofluorescence assay using Crohn's disease tissue-injected athymic nude mouse lymph nodes in the diagnosis of inflammatory bowel diseases.

Sometimes, even after extensive investigative efforts, the diagnosis of inflammatory bowel disease remains in doubt. The accurate diagnosis is important if appropriate therapy is to be instituted. A simple indirect immunofluorescence assay that tests the patient's serum against lymphoid tissues from athymic nude (nu/nu) mice receiving injections of filtrates of Crohn's disease tissue is proposed. Eighty percent of serum samples from patients with active, symptomatic Crohn's disease give positive results of immunofluorescence when tested with these lymphoid tissues. The false-positive rate has been very low (less than 10 percent). Because this assay is fairly sensitive and least invasive, it was used for the clarification of many puzzling cases that were seen at the Albert Einstein College of Medicine over the past three years. Ten of these cases were selected for illustration and discussion and are presented in this report.