HOST RISK-FACTORS FOR THE DEVELOPMENT OF REACTIVE ARTHRITIS - A FAMILY STUDY

Objective. To determine if the same arthritogenic microorganisms can t rigger reactive arthritis (ReA) in both HLA-B27 positive and HLA-B27 n egative individuals. To determine risk factors (other than HLA-B27) fo r the development of ReA. Methods. Following a common food source outb reak of Salmonella enteritidis, 2 family groups of individuals with dy sentery and new onset ReA signs and symptoms were identified. HLA typi ng was performed for all family members exposed to the dysenteric orga nism. Results. ReA occurred in HLA-B27 positive members of Family A. N o member of Family B possessed HLA-B27 or CREG phenotype, but 3 member s developed ReA. The HLA identical sibling of the proband in Family B developed dysentery but did not develop ReA. Conclusion. In this epide mic, interaction of the microorganism with an HLA-B27 positive host pr edictably produced ReA but B27 was not necessary to produce it in othe r dysenteric patients. Host factors including amount of ingested micro organisms, age and sex but excluding HLA type may account for the diff erential development of ReA in the siblings in Family B.