Four new members expand the interleukin-1 superfamily

We report here the cloning and characterization of four new members of the interleukin-1 (IL-1) family (FIL1 delta, FIL1 epsilon, FIL1 zeta and FLI1 eta, with FIL1 standing for "Family of IL-1"), The novel genes demonstrate significant sequence similarity to IL-1 alpha, IL-1 beta, IL-1ra, and IL-18, and in addition maintain a conserved exon-intron arrangement that is shared with the previously known members of the family. Protein structure modeling also suggests that the FIL1 genes are related to IL-1 beta and IL-1ra. The novel genes form a cluster with the IL-1s on the long arm of human chromosome 2.