Immunoglobulins in the pathophysiology of visceral leishmaniasis

Abstract

Hypergammaglobulinemia is a common feature associated with visceral leishmaniasis (VL). It has been well accepted that cell-mediated immunity supported by Th1 responses provides protection against Leishmania infection. On the other hand, the role of humoral immunity in control or exacerbation of VL has been less clear, despite that the presence of strong humoral responses is the hallmark of patients with VL. Such the high level of antibody seen in VL patients is often utilized for serological diagnostic tests, including commercial enzyme-linked immunosorbent assay (ELISA) tests and rK39 dipstick tests. Because many studies have demonstrated that antibody titers in those serodiagnostic tests are higher in active VL patients compared with the asymptomatic, humoral responses may be involved in the development of symptoms during VL. However, the physiological and pathological roles of the humoral responses during VL remain elusive. In this chapter, we discuss the components of antibodies, activation mechanisms of humoral responses, and the pathological mechanisms of immunoglobulin activity during VL.