Functional Studies of Chicken Histocompatibility Antigens Bearing Ig V-like Domains

最近在确定鸡主要组织相容性复合体中编码的高度多态的B-G抗原的结构方面取得了重大进展。目前已确定B-G抗原是一个分子家族，其不同成员除表达于包括免疫系统细胞在内的红细胞外，还表达于多种不同组织的细胞上。对一些B-G家族成员的序列测定揭示了B-G多态的结构基础，包括免疫球蛋白v样结构域中存在高度可变的序列多样性。B-G胞质尾巴由不同序列的七肽重复序列组成。B-G抗原存在于肠道的上皮细胞、肝脏的细胞、血小板(鸟类的高度吞噬细胞)、一些淋巴细胞以及法氏囊和拇指的间质细胞上。这个项目的目的是试图根据新发现的表达B-G分子的部位来确定B-G抗原的功能。B-G抗原长期以来被称为鸡的血型抗原。直到最近，B-G抗原还被认为只在红细胞上表达。目前已知，在雏鸡发育的不同阶段，它们在各种细胞类型和组织中都有表达。此外，通过DNA测序工作表明，它们在结构上与免疫球蛋白基因相似。这些新的观察结果导致了B-G抗原可能在鸡的免疫系统中发挥某些作用的假设。本研究的目的是探索这一假说。这项研究的结果有可能为了解鸡的免疫系统如何运作提供新的线索。

Significant progress was made recently in defining the structure of the highly polymorphic B-G antigens encoded within the major histocompatibility complex of the chicken. It has been determined that B-G antigens are a family of molecules, divergent members of which are expressed on cells in several different tissues in addition to erythrocytes, including immune system cells. Determination of the sequences of some of the B-G family members has revealed the structural basis of B-G polymorphism, including the presence of hypervariable sequence diversity within an immunoglobulin v-like domain. B-G cytoplasmic tails are made up of heptad repeats of diverse sequence. B-G antigens have been found on the epithelia in the gut, cells in the liver, thrombocytes (highly phagocytic cells in birds), some lymphocytes, and cells within the stroma of the bursa and thumus. The objective of this project is to attempt to define the function (or functions) of the B-G antigens in light of the newly recognized sites where B-G molecules are now known to be expressed. The B-G antigens have long been known as blood group antigens of chickens. Until recently, the B-G antigens were thought to be expressed exclusively on red blood cells. They are now known to be expressed in various cell types and tissues throughout the chick, at various stages of development. Furthermore, they have been shown through DNA sequencing work to have structural resemblance to immunoglobulin genes. These new observations have led to the hypothesis that the B-G antigens may play some role in the chicken immune system. The goal of this study is to explore this hypothesis. The results of this study have the potential to shed new light on how the immune system of the chicken operates.