IgD的发现已有21年了,尽管分子和细胞免疫学有进展但对其确切功能仍然不清楚。人血清中IgD含量甚微,鼠血清中含量更少,现仍检测不出。但大部分B细胞表面有IgD,其重要性可能是做为一种膜表面受体。人IgD的重链是有四个功能区的重链,由一个Fc段和一个易变的Fab组成。Fc段对蛋白酶的水解作用具有极大的抵抗力。鼠IgD的重链似乎仅有三个稳定区。IgD最显著的结构特征是有一长的绞链 The discovery of IgD has been around for 21 years and its exact function remains unclear, despite advances in molecular and cellular immunology. Human serum IgD content is very small, less content in rat serum, is still undetectable. However, most of the B cell surface IgD, its importance may be as a membrane surface receptors. The heavy chain of human IgD is a heavy chain with four functional regions, consisting of an Fc segment and a variable Fab. The Fc segment is highly resistant to proteolytic hydrolysis. The heavy chain of murine IgD seems to have only three stable regions. The most prominent structural feature of IgD is a long hinge