Cellular Interactions in the Humoral Immune Response

This chapter discusses the interactions between T and B cells and the role of accessory cells and cytokines in the generation of specific antibody responses. The first part of the chapter is a historic perspective followed by a summary of the present-day concepts. The final part of the chapter speculates on how the different components of the immune system might function in vivo. A highly complex system of communication has developed among the various cell types in the immune sytem. One important mechanism of communication is the requirement for interactions among cells for the activation and differentiation of resting B lymphocytes into antibody-secreting cells. These cellular interactions involve both cell-cell contact and the release of mediators (cytokines) that can act in either an autocrine or paracrine fashion on cells both within and outside the immune system. The chapter describes two types of functionally different Th cells and the role of lymphokines in the regulation of T and B cell function. Although Th1 versus Th2 cells have different effects on B cells and other cells in vitro, their role in vivo is less well understood. Nonetheless, studies in vivo have confirmed the requirement for IL-4 and IFN-У in IgE and IgG2, responses, respectively.