SECRETORY IMMUNE-RESPONSE AND CLINICAL SEQUELAE OF SALMONELLA INFECTION IN A POINT-SOURCE COHORT

Objective. To determine the kinetic isotypic serum and secretory immun e response to Salmonella enteritidis in a cohort of individuals expose d to the organism in a single food source outbreak of dysentery. To de termine the clinical outcome and immunogenetics of the exposed cohort and to correlate these features with the immune response. Methods. Fol lowing a single point source outbreak of Salmonella enteritidis, a coh ort of dysenteric individuals were ascertained using a reactive arthri tis screening questionnaire (QUEST). Serum and stimulated saliva sampl es were obtained at 6, 12, and 24 months following the outbreak of dys entery; examinations were conducted at the same time. Two unexposed co ntrol groups were ascertained: (1) general rheumatology clinic patient s and (2) well nonarthritic family practice patients. An ELISA to dete rmine quantitative IgA responses to Salmonella enteritidis lipopolysac charide (LPS) was performed. Results. Eleven of the 84 exposed individ uals with dysentery developed reactive arthritis (ReA) or reactive ent hesitis (ReE). There was a prolonged salivary IgA anti-LPS response in both the ReA/ReE and DYS (dysentery atone) patients compared with une xposed controls. A ratio of salivary IgA anti-LPS/serum IgA anti-LPS > 1 was associated with a good outcome (remission) of ReA, whereas a ra tio < 1 was associated with chronic disease. Conclusions. There is a m ore prolonged humoral immune response to Salmonella LPS in exposed ind ividuals than hitherto described. A risk factor in the prolongation of ReA is the inability to mount an appropriate specific salivary (secre tory) immune response.