A longitudinal study of peripheral blood mononuclear cell proliferative responses to bacterial antigens in reactive arthritis.

Reactive arthritis (ReA) is a sterile inflammatory arthritis which usually occurs after an enteric or genitourinary infection. In recent years it has been recognized that synovial fluid mononuclear cells from an affected joint demonstrate marked proliferative responses if incubated with preparations of the organism triggering the arthritis; peripheral blood mononuclear cell (PBMC) responses are typically much smaller. One interpretation of this finding is that recognition of the triggering organism is enhanced within the joint compared to peripheral blood, but it could also be argued that the PBMC responses are actually depressed during acute arthritis. We have examined this possibility in a longitudinal study of PBMC proliferative responses in patients with ReA. In this study we have demonstrated that PBMC proliferative responses to the triggering organism were indeed depressed during acute ReA, and showed a significant increase after recovery from the arthritis. These findings also applied to PBMC recognition of the recall antigen PPD, and to the response to IL-2.