In contrast, Th2 cells selectively produce cytokines such as interleukin-4 (important for producing anaphylactic antibodies of immunoglobulin E class, IgE), interleukin-5 (the major growth factor for eosinophils and a critical regulator of antibody production by some B lymphocytes), interleukin-6 (a major mediator of the systemic acute phase reactions, and a nonspecific enhancer of antibody production) and interleukin-13 (also involved in promoting IgE synthesis, as well as in many of the tissue phenomena associated with allergic reactions and asthma). This evidence concerns the gene IL4 and allergic disease.