The role of T/B cell interactions and cytokines in the regulation of human IgE synthesis.

Induction of immunoglobulin (Ig) isotype switching and isotype production by human B cells requires contact-mediated signals delivered by T helper cells in combination with cytokines. Effective T cell help requires T cell activation resulting in a rapid expression of T cell membrane proteins, which interact with ligands constitutively expressed on B cells. These interactions lead to B cell activation, proliferation and, in the presence of cytokines, to isotype switching and immunoglobulin synthesis. The nature of the T cell antigens involved in these T/B cell interactions, and their role in human B cell activation resulting in IgE synthesis in the presence of IL-4 and IL-13, will be discussed.