Application of an Immunofluorescence Assay for Crohn's Disease Using Primed Nude Mouse Lymph Nodes to a United States/Mexican Border Population

ABSTRACT Previous studies using an indirect immunofluorescence (IF) technique found that sera from patients with Crohn's disease (CD) frequently contained antibody that recognized an antigen(s) in CD tissue filtrate-primed lymphoid tissue from athymic nude (nu/nu) mice. The present study examined the reproducibility of this IF assay in a different laboratory setting and used patients with infectious diarrhea. We examined the immunoreactivity of 113 sera from eight patients with Crohn's disease, 11 with ulcerative colitis, 62 patients with infectious diarrhea, 22 nondiarrheal disease controls, and ten normal adults. Sera were absorbed with nu/+ BALB/c mouse serum proteins coupled to Sepharose 4B to remove nonspecific binding. All sera were coded and tested against at least 2 of 4 lymph nodes from nu/nu mice that were previously inoculated with either CD tissue filtrate or with a passaged CD-induced nu/ nu lymphoma. Reference positive CD sera and negative control sera were run in parallel during each assay. Sera from three CD patients consistently showed positive IF. None of the sera from patients with infectious diarrhea, other disease controls, or normals were positive. These results demonstrate the reproducibility of the IF assay using CD tissue-primed nude mouse lymph nodes and the preferential immunoreactivity of CD sera.