Ewald S J, Lien Y Y, Li L, Johnson L W
Department of Pathobiology, Auburn University, AL 36849-5519, USA.
Vet Immunol Immunopathol. 1996 Oct;53(3-4):285-301. doi: 10.1016/s0165-2427(96)05613-9.
The major histocompatibility (B) complex of the chicken contains genes similar to Class I (B-F) and Class II (B-L beta) genes in mammals, as well as a highly-polymorphic gene family (B-G) whose exact function is not known. Specific B-haplotypes are strongly associated with resistance to a number of infectious diseases, and with immune responses to soluble and cellular antigens. In mammals, Class I and Class II molecules control development of the T cell repertoire, including selection of CD4+ and CD8+ T cells. One study of chickens reported that low CD4:CD8 ratio was associated with the B4 haplotype, which shares expressed B-F/B-L genes with the B13 haplotype. In studies reported here, chickens of two haplotypes carried in the Auburn R line, B302 and B305 (which is B13-related), were evaluated for percentages of T cells expressing the CD4, CD8, CD3, TCR1, TCR2 and TCR3 antigens in peripheral blood lymphocytes (PBL), thymus, and spleen. These two haplotypes were chosen for comparison because they differ in resistance to Marek's disease (MD) and are closely-related in B-F and B-L genes by restriction fragment length polymorphism analyses. Homozygous birds of each B haplotype were produced from crosses of (B302 x B305)F1 sires and dams. PBL, thymocytes, and splenocytes from B302 homozygotes had higher CD4:CD8 ratios than B305 homozygotes. However, CD4:CD8 ratio differences could not be attributed to haplotype-controlled differences in V beta usage within CD4/CD8 subsets, as has been described for certain V beta families in mice and humans. These results indicate that thymic selection events involving CD4 and CD8 subsets and TCR V beta usage are controlled by a gene or genes closely-linked to the B-complex, which may or may not be Class I or Class II genes.
鸡的主要组织相容性（B）复合体包含与哺乳动物的I类（B-F）和II类（B-Lβ）基因相似的基因，以及一个功能尚不明确的高度多态基因家族（B-G）。特定的B单倍型与对多种传染病的抗性以及对可溶性和细胞性抗原的免疫反应密切相关。在哺乳动物中，I类和II类分子控制T细胞库的发育，包括CD4+和CD8+T细胞的选择。一项对鸡的研究报告称，低CD4:CD8比率与B4单倍型相关，B4单倍型与B13单倍型共享表达的B-F/B-L基因。在本文报道的研究中，对奥本R系中携带的两种单倍型B302和B305（与B13相关）的鸡，评估其外周血淋巴细胞（PBL）、胸腺和脾脏中表达CD4、CD8、CD3、TCR1、TCR2和TCR3抗原的T细胞百分比。选择这两种单倍型进行比较是因为它们对马立克氏病（MD）的抗性不同，并且通过限制性片段长度多态性分析在B-F和B-L基因上密切相关。每种B单倍型的纯合子鸡由（B302×B305）F1代的公母杂交产生。B302纯合子的PBL、胸腺细胞和脾细胞的CD4:CD8比率高于B305纯合子。然而，CD4:CD8比率差异不能归因于单倍型控制的CD4/CD8亚群内Vβ使用差异，就像在小鼠和人类某些Vβ家族中所描述的那样。这些结果表明，涉及CD4和CD8亚群以及TCR Vβ使用的胸腺选择事件由与B复合体紧密连锁的一个或多个基因控制，这些基因可能是也可能不是I类或II类基因。
