Cytokines are protein messengers that carry information from cell to cell[<cite idref="PUB00003320"/>]. Interleukin is one such molecule, and participates in several B-cell activation processes: e.g., it enhances production and secretion of IgG1and IgE [<cite idref="PUB00004616"/>]; it induces expression of class II major histocompatability complex (MHC) molecules on resting B-cells; and it regulates expression ofthe low affinity Fc receptor for IgE on lymphocytes and monocytes.Interleukin-4 (IL4) has a compact, globular fold (similar to othercytokines), stabilised by 3 disulphide bonds [<cite idref="PUB00000339"/>]. One half of the structureis dominated by a 4 alpha-helix bundle with a left-handed twist [<cite idref="PUB00002742"/>]. Thehelices are anti-parallel, with 2 overhand connections, which fall into a2-stranded anti-parallel beta-sheet [<cite idref="PUB00002742"/>]. Interleukin-4