Patricia Kilian

Human interleukin-1α is chemotactic for normal human keratinocytes

Abstract Interleukin-1 (IL-1)has been shown to have mitogenic and chemotactic properties for a variety of cell types includes keratinocytes [1, 2, 19, 20, 23]. These studies suggested that keratinocytes possess receptors for IL-1. In this study, the chemotactic properties of IL-1 for keratinocytes were confirmed and IL-1 receptors were demonstrated on keratinocytes using a radio receptor assay. Crosslinking studies with IL-1α identified two major bands of M r 97 kDa and 133 kDa. Thus, keratinocytes possess high affinity IL-1 receptors and respond to IL-1 by directed migration.

Chapter 18. Interleukin 1

Publisher Summary This chapter discusses the biochemical characterization and the physiological role of interleukin 1 (IL-1). IL-1 is a molecule that possesses a wide variety of biological activities. Biochemical studies reveal that IL-1 produced by stimulated murine macrophages and macrophage tumor cell lines is a single polypeptide chain. Human IL-1 has been shown to be produced by stimulated normal human peripheral blood leukocytes or monocytes, leukemic cells, and a number of human tumor cell lines. Murine and human keratinocytes have been shown to produce an IL-1-like activity designated epidermal T-cell activating factor. This factor exhibits some of the activities of IL-1. IL-1 appears to play a key role in the activation of T-lymphocytes. The processes triggered by IL-1 may include both the secretion of IL-2 and induction of receptors for this growth factor. IL-1 can also modulate B-cell function. However, the nature of the effect can vary depending on the presence of other lymphocyte-derived signals and the type of B-cell stimulus. An effect of IL-1 on fibrinogen and haptoglobin synthesis has also been discussed in the chapter. IL-1 may also be a modulator of the fibroblast proliferation. IL 1 has also significant effects on the cartilage, bone, and synovial membrane. IL-1 is thought to be an important mediator of immune cell interactions and to contribute to a number of disease manifestations and physiological processes. Thus, agents that modulate either IL-1 production or IL-1 activity on the target tissues may be therapeutically beneficial and have been the focus of a number of investigations. This information and additional developments in IL-1 research should lead to an understanding of the mechanism, by which IL-1 induces each of its effector activities, of the role of IL-1 in various disease states and of the means, by which specific activities of IL-1 can be modulated.

The role of arginine residues in interleukin 1 receptor binding.

Interleukin 1 (IL-1) is a family of polypeptide cytokines that plays an essential role in modulating immune and inflammatory responses. IL-1 activity is mediated by either of two distinct proteins, IL-1 alpha or IL-1 beta, both of which bind to the same receptor found on T-lymphocytes, fibroblasts and endothelial cells (Type 1 receptor). The effect of specific chemical modification of recombinant IL-1 alpha and IL-1 beta on receptor binding was examined. Modification of the proteins with phenylglyoxal, an arginine-specific reagent, resulted in the loss of Type 1 IL-1 receptor binding activity. The stoichiometry of this modification revealed that a single arginine in either IL-1 alpha or IL-1 beta is responsible for the loss of activity. Cyanogen bromide cleavage of phenylglyoxal modified IL-1 alpha and IL-1 beta, followed by sequencing of the peptides, revealed that arginine-12 in IL-1 alpha and arginine-4 in IL-1 beta, which occupy the same topology in the respective crystallographic structures, are the target of phenylglyoxal. These results suggest that an arginine residue plays an important role in ligand-receptor interaction.

Purification to homogeneity and amino acid sequence analysis of a receptor protein for interleukin 1

The interleukin 1 (IL-1) receptor from mouse EL-4 thymoma cells was purified to homogeneity by a method which utilized ligand affinity chromatography and classical chromatographic techniques. After solubilization of the receptor from intact cells with the zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate, the IL-1 binding activity was purified greater than 23,000-fold. Analysis of the purified protein by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immunoblot, and ligand blot demonstrated that a single protein of molecular mass of approximately 80 kDa is the IL-1 binding polypeptide. The purified protein bound IL-1 with a dissociation constant of approximately 1.1 X 10(-10) M, which is indistinguishable from the affinity of the cell-bound receptor. The amino acid composition of this protein is strikingly similar to the composition deduced from the sequence of a cDNA coding for an IL-1 receptor from EL-4 cells. Protein sequence analysis of Staphylococcus aureus V-8 protease-derived peptides yields data consistent with the sequence proposed from cloned cDNA. These studies have demonstrated that the high affinity IL-1 receptor on EL-4 cells is the 80-kDa protein.