Chapter 5 - Regulation of Humoral Immunity by CD1d-Restricted Natural Killer T Cells

Abstract

Humoral immunity is of immense importance in health and disease, being both beneficial and deleterious. Vaccine- or infection-stimulated antibody-mediated protection against pathogens is critical in host defense, but pathogen-specific antibodies can also aid infectious processes or drive pathology. Loss of immunological tolerance is associated with production of self-reactive antibodies that can worsen the disease, and loss of growth regulation can lead to several types of B cell malignancies. For these reasons and others, it is incumbent on researchers to continue to understand how humoral immunity is regulated. In the past 10–15 years, it has become apparent that CD1d-restricted Natural Killer T (NKT) cells can enhance humoral immunity against T-dependent and T-independent antigens. Furthermore, NKT cells promote B cell memory and the longevity of antibody-secreting plasma cells. NKT cells potentially have profound consequences for vaccine development and understanding the immune response to pathogens. This chapter introduces NKT cells and their known biological functions and discusses specific examples of NKT cells advancing humoral immunity. Available information on the mechanisms of action by which NKT cells impact B cell activation, and commitment to B cell memory or effector functions and plasma cell longevity are also reviewed.