Objective: To determine the kinetic isotypic serum and secretory immune response to Salmonella enteritidis in a cohort of individuals exposed to the organism in a single food source outbreak of dysentery. To determine the clinical outcome and immunogenetics of the exposed cohort and to correlate these features with the immune response.
Methods: Following a single point source outbreak of Salmonella enteritidis, a cohort of dysenteric individuals were ascertained using a reactive arthritis screening questionnaire (QUEST). Serum and stimulated saliva samples were obtained at 6, 12, and 24 months following the outbreak of dysentery; examinations were conducted at the same time. Two unexposed control groups were ascertained: (1) general rheumatology clinic patients and (2) well nonarthritic family practice patients. An ELISA to determine quantitative IgA responses to Salmonella enteritidis lipopolysaccharide (LPS) was performed.
Results: Eleven of the 84 exposed individuals with dysentery developed reactive arthritis (ReA) of reactive enthesitis (ReE). There was a prolonged salivary IgA anti-LPS response in both the ReA/ReE and DYS (dysentery alone) patients compared with unexposed controls. A ratio of salivary IgA anti-LPS/serum IgA anti-LPS > 1 was associated with a good outcome (remission) of ReA, whereas a ratio < 1 was associated with chronic disease.
Conclusions: There is a more prolonged humoral immune response to Salmonella LPS in exposed individuals than hitherto described. A risk factor in the prolongation of ReA is the inability to mount an appropriate specific salivary (secretory) immune response.