Sharing of the interleukin-2 (IL-2) receptor gamma chain between receptors for IL-2 and IL-4

Cellular response of protozoan parasites to host-derived cytokines

Cytokines are extracellular signalling molecules, produced by different cell types and displaying a wide range of activities such as the induction or inhibition of target cell survival, proliferation and differentiation. When directly interacting with different parasites, cytokines exert similar activities, acting as growth factors and, in one of the examples given here, also enhancing parasite survival. The importance of this interaction in the natural history of parasitic diseases as well as the selective forces maintaining functional cytokine 'receptors' in protozoan parasites is discussed in this review by Marcello Barcinski and Maria Elisabete Costa-Moreira.

Multimeric cytokine receptors

Cytokines are pleiotropic regulators that control proliferation, differentiation, and other cellular functions. They play a pivotal role in the immune and hematopoietic systems, and subsets of cytokines often exhibit similar biologic activities in common target cells. Recent cloning of genes for the cytokine receptors has provided new insights into the understanding of how the cytokines control the immune and hematopoietic systems. Cytokine receptors usually consist of multiple subunits, most of which belong to a new gene family called the cytokine receptor superfamily, and receptors for a subset of cytokines with similar functions share a common subunit with a signaling function, providing a molecular basis for the functional redundancy of cytokines.