B cell-Mediated Autoimmune Diseases
The body’s immune system, which is designed to protect the body from infection and cancer, includes B cells and T cells. B cells are responsible for producing antibodies against antigens that the body perceives as foreign whereas T cells are responsible for cell-mediated immunity. In the case of B cell-mediated autoimmune diseases, certain populations of the patient’s B cells mistakenly produce antibodies directed against normal tissues and cells, leading to disease. While these autoantibodies are the major effectors of B cell-mediated autoimmune diseases, the underlying root cause of each B cell-mediated autoimmune disease is the defective B cells that mistakenly make these pathogenic antibodies. These pathogenic B cells express autoantibodies on their surfaces with the same antigen specificity as the circulating pathogenic autoantibodies, which can be used to distinguish them from the healthy B cell population, as shown in the figure below.
Current treatment options for autoimmune mediated diseases involve generalized immune suppression, achieved through corticosteroids, immunosuppressive medications and biologics. Most commonly, corticosteroids are used on both a chronic and acute basis to control disease, and act via a variety of mechanisms to control or downregulate multiple inflammatory pathways. Currently existing treatment options target parts of the immune system in addition to disease-causing B cells, and in general require chronic administration to reduce recurrence rates and are associated with potentially life-threatening side effects. The ideal therapy in autoimmune diseases would completely and specifically eliminate the pathogenic B cells while sparing the immune cells that protect against infection, without requiring chronic administration.