Tominaga A, Takaki S, Hitoshi Y, Takatsu K
Department of Biology, Kumamoto University Medical School, Japan.
Bioessays. 1992 Aug;14(8):527-33. doi: 10.1002/bies.950140806.
Interleukin 5 (IL-5) is a kind of peptide hormone released from T lymphocytes of mammals infected with microorganisms or parasites. It is an acidic glycoprotein with a molecular mass of 40 to 50 kDa that consists of a homodimer of polypeptides. It controls hematopoiesis so that it increases natural immunity. In the mouse, IL-5 acts on committed B cells to induce differentiation into Ig-producing cells and on common progenitors for CD5+ pre-B cells and CD5+ macrophages to support their survival. The antibodies secreted by CD5+ B cells seem to be responsible for the primary protection against the infection with microorganisms or parasites. It also supports the growth and/or differentiation of eosinophil precursor and mature eosinophils, which can be effective for the removal of parasites in combination with the antibodies against them. Murine IL-5 receptor (IL-5R) consists of two different polypeptide chains; alpha chain and beta chain. The IL-5R alpha chain is 60 kDa protein that binds IL-5 with low affinity. The IL-5R beta chain is a 130 kDa protein which does not bind IL-5 by itself but is necessary to form the high affinity IL-5R. The beta chain was identified by using one of the anti-IL-5R mAb and anti-IL-3R mAb as the IL-3R homologue. This beta chain is also used as the beta chain of GM-CSF receptor. This fact suggests that there is a common signaling mechanism among these cytokines and efficient cooperation among them. At the same time, these findings may explain the overlapping role of these cytokines in the development of granulocytes.
白细胞介素5（IL-5）是一种由感染微生物或寄生虫的哺乳动物T淋巴细胞释放的肽类激素。它是一种酸性糖蛋白，分子量为40至50 kDa，由多肽同二聚体组成。它控制造血作用，从而增强天然免疫力。在小鼠中，IL-5作用于定向B细胞，诱导其分化为产生Ig的细胞，并作用于CD5 +前B细胞和CD5 +巨噬细胞的共同祖细胞，以支持它们的存活。CD5 + B细胞分泌的抗体似乎负责对微生物或寄生虫感染的主要保护作用。它还支持嗜酸性粒细胞前体和成熟嗜酸性粒细胞的生长和/或分化，与针对它们的抗体结合可有效清除寄生虫。小鼠白细胞介素5受体（IL-5R）由两条不同的多肽链组成；α链和β链。IL-5Rα链是一种60 kDa的蛋白质，与IL-5的结合亲和力较低。IL-5Rβ链是一种130 kDa的蛋白质，其本身不结合IL-5，但对于形成高亲和力的IL-5R是必需的。通过使用抗IL-5R单克隆抗体和抗IL-3R单克隆抗体之一作为IL-3R同源物鉴定出β链。该β链也用作GM-CSF受体的β链。这一事实表明这些细胞因子之间存在共同的信号传导机制以及它们之间的有效协作。同时，这些发现可能解释了这些细胞因子在粒细胞发育中的重叠作用。
