Lymphocyte transformation responses to gram negative bacteria after Yersinia and Salmonella infection: the importance of enterobacterial common antigen for the response.

Increased lymphocyte transformation (LT) responses have been observed in Yersinia infections both against the causative bacterium and against other enterobacteria. The responses of patients with reactive arthritis are lower than those of non-arthritic patients. We have now studied the LT responses against several gram negative bacteria and against a pair of enterobacterial common antigen (ECA) positive and ECA negative Salmonella typhimurium strains in patients after Yersinia or Salmonella infection. The haptenic ECA alone seemed not to be responsible for the increased LT responses. We conclude that some other common antigenic determinants present on the bacteria are responsible for the LT response.