The result of testing for colocalization of LPS and TLR4 was positive in 8 of 10 patients with active EoE (80.0%), 1 of 9 patients with inactive EoE (11.1%), and 1 of 10 control patients (10.0%), with greater colocalization of H influenzae LPS and TLR4 staining density in the samples from patients with active EoE than in the controls or the patients with inactive EoE (P = .009 and P = .018, respectively). The gene discussed is TLR4; the disease is eosinophilic esophagitis.