B lymphocytes produce antibodies that augment host defenses via their capability for recognizing infectious agents, toxins, and other virulence factors with great specificity and high affinity. The adaptive immune system is remarkable; a limited repertoire of germ-line precursor genes can be recombined to produce antibodies with virtually any binding specificity. Therefore, antibodies play central roles in the defense from external threats that include bacteria and viruses. In turn, microbial pathogens have developed virulence factors that subvert host defenses by targeting secreted antibodies and their membrane-associated forms (such as B-cell receptors, BCR).

In the B-cell Immunobiology Lab, we are investigating how putative microbial B-cell superantigens affect in vivo B-cell repertoires (see Silverman and Goodyear, Nature Reviews in Immunology, 2006). As shown below (see figure 1), we reported the first B-cell repertoire surveys using next generation sequencing that showed the capacity of limited exposure to prototypic B-cell superantigen induced global shifts in the in vivo B-cell repertoire that reflected binding interactions of a major subset of BCR with Protein L (Grönwall et al., 2012, Journal of Immunology) (see figure 1). For these analyses we worked with Sergei K. Pond and colleagues on a high throughput computational pipeline that will now be applied to human repertoires (see Frost et al., 2015, Philos Trans R Soc Lond B Biol Sci)(see figure 2).

In autoimmune diseases, such as systemic lupus erythematosus (SLE), high levels of circulating autoantibodies are a hallmark of the disease, and animal models have confirmed that disease and premature death occur only after the skewing of the B-cell repertoire toward autoreactivity. While the pathophysiology of SLE is complex, there is overwhelming evidence that pathogenic autoantibodies are largely responsible for the organ damage, particularly the renal disease that is the primary cause of disability and death. We are investigating antibody responses in the gut and in the periphery in both human and murine systems to better understand the initiators and drivers of this autoimmune disease.