Prominent T cell response to a selectively in vivo expressed Borrelia burgdorferi outer surface protein (pG) in patients with Lyme disease

Diagnosis of Lyme disease by analysis of T cell immune responses in vitro i s curtailed by poor correlation between test results and status of infectio n. This is probably due to the inherent nonspecific activation potential of the causative agent, the spirochete Borrelia burgdorferi, for bystander ly mphocytes, in particular via their outer surface lipoproteins. We have now applied a novel protocol to determine specific T cell responses in Lyme dis ease patients and exclude unrelated cellular responses in vitro. Non-lipida ted spirochetal antigens (OspA, OspC and P39) including those selectively e xpressed in the mammalian host (pG and BapA) were used for antigenic stimul ation and autologous dendritic cells served as antigen-presenting cells. Th e majority of patients with well-defined early and late manifestations of L yme disease exhibited specific T cell proliferative responses to one or mor e of the indicated antigens, however at distinct levels. Most notably, amon g the five antigens tested, pG was specifically recognized by the majority of T cell populations (>70%) - mainly Th1 cells - from patients but not con trol individuals. These data indicate a causal relationship between B. burg dorferi infection and T cell reactivity to pG, thus making this protein a p romising additional diagnostic marker for Lyme disease.