Interleukin 4

Overview
Interleukin-4, abbreviated IL-4, is a cytokine that induces differentiation of naive helper T cells (Th0 cells) to Th2 cells. Upon activation by IL-4, Th2 cells subsequently produce additional IL-4. The cell that initially produces IL-4, thus inducing Th0 differentiation, has not been identified.

Functions
It has many biological roles, including the stimulation of activated B-cell and T-cell proliferation, and the differentiation of CD4+ T-cells into Th2 cells.

It is a key regulator in humoral and adaptive immunity.

IL-4 induces B-cell class switching to IgE, and up-regulates MHC class II production.

History
This cytokine was co-discovered by Maureen Howard and William Paul and by Dr. Ellen Vitetta and her research group in 1982.

The nucleotide sequence for human IL-4 was isolated four years later confirming its similarity to a mouse protein called B-cell stimulatory factor-1 (BCSF-1).

Related Chapters

 * STAT6