Delays and Diversions Mark the Development of B Cell Responses to Borrelia burgdorferi Infection

Abstract

B cell responses modulate disease during infection with Borrelia burgdorferi, the causative agent of Lyme disease, but are unable to clear the infection. Previous studies have demonstrated that B. burgdorferi infection induces predominantly T-independent B cell responses, potentially explaining some of these findings. However, others have shown effects of T cells on the isotype-profile and the magnitude of the B. burgdorferi-specific antibodies. This study aimed to further investigate the humoral response to B. burgdorferi and its degree of T cell-dependence, with the ultimate goal of elucidating the mechanisms underlying the failure of effective immunity to this emerging infectious disease agent. Our study identifies distinct stages in the B cell response using a mouse model, all marked by the generation of unusually strong and persistent T-dependent and T-independent IgM antibodies. The initial phase is dominated by a strong T-independent accumulation of B cells in lymph nodes and the induction of specific antibodies in the absence of germinal centers. A second phase begins around week 2 ½ - 3, in which relatively short-lived germinal centers develop in lymph nodes, despite a lymph node architecture that lacks clearly demarcated T and B cell zones. This response failed, however, to generate appreciable numbers of long-lived bone marrow plasma cells. Finally, there is a slow accumulation of long-lived antibody-secreting plasma cells in bone marrow, reflected by a strong, but ultimately ineffective serum antibody response. Overall, the study indicates that B. burgdorferi might evade B cell immunity by interfering with its response kinetics and quality.

CD4+T Cells Promote Antibody Production but Not Sustained Affinity Maturation during Borrelia burgdorferi Infection

“…B. burgdorferi Arp-and DbpA-specific enzyme-linked immunosorbent assays (ELISAs) were performed as described above using 2.5 g/ml Arp and 0.5 to 1 g/ml DbpA as a coating, revealing bound serum IgG with goat anti-mouse IgG (Southern Biotech). B. burgdorferi-specific IgG was measured using a cocktail of 2.5 g/ml each of Arp, DbpA, OspC, and BmpA and revealing serum antibodies with goat anti-mouse IgG (Southern Biotech) (18). For index ELISAs, immediately following a 2-h incubation with serum, duplicate wells were incubated with PBS or 6 M urea (in PBS) for 5 min.…”

“…For index ELISAs, immediately following a 2-h incubation with serum, duplicate wells were incubated with PBS or 6 M urea (in PBS) for 5 min. Detection steps were as described previously (18), except that for all subsequent wash steps, plates were washed 5 times with PBS (omitting the previously described PBS-Tween and distilled water wash steps). The avidity index was calculated as the ratio of antibody detected with urea wash to total antibody detected by PBS wash; in other words, the ratio of high avidity to total antibody in the serum.…”

“…Recombinant DbpA from cN40 was produced by GenScript. The detection of the number of FlaB copies per mg of tissue by quantitative PCR (qPCR) was done as previously described (18).…”

“…Strong evidence links infection-induced, antibody-mediated immunity to the control of B. burgdorferi tissue burden and to disease resolution (4,14,15) but not to the clearance of B. burgdorferi infection (16,17). Paradoxically, existing literature suggests that the presence of CD4 T cells does not measurably enhance the disease-ameliorating humoral response to B. burgdorferi (8), which may be explained by an induction of strong disease-resolving T cell-independent B cell responses (8,18). However, it appears unlikely that the protective B cell response to B. burgdorferi, a highly complex pathogen expressing many immunogenic surface antigens (19), is confined to T-independent antibody responses alone.…”

“…Our recent studies suggested that germinal center responses were nonfunctional after primary B. burgdorferi infection, as long-lived antibody-secreting plasma cells (18) and memory B cells (R. A. Elsner, C. J. Hastey, and N. Baumgarth, unpublished data) were not induced for months after infection (18). Importantly, a coadministered influenza vaccine antigen similarly failed to induce long-term immunity when given during B. burgdorferi infection (Elsner et al, unpublished).…”