问题 问答题 简答题

在TI抗原引起的免疫应答中,B1细胞的活化机制:TI抗原可分为I型TI抗原和II型TI抗原,在TI抗原引起的体液免疫应答中,其诱导B1细胞活化的机制不同。

答案

参考答案:

(1)I型TI抗原(如细菌脂多糖和聚合鞭毛素等)诱导Bl细胞活化的机制为:B1细胞通过表面抗原受体(SIgM)与I型TI抗原表面特异性抗原决定簇结合,产生第一信号;通过表面有丝分裂原受体与I型TI抗原表面相应有丝分裂原结合,产生第二信号。B1细胞接受双信号作用后活化。

(2)II型TI抗原(如肺炎球菌荚膜多糖和D-氨基酸聚合物等),表面具有多个重复出现的抗原决定簇,呈线状排列。这些抗原决定簇在体内不易降解,对B1细胞抗原受体亲和力强,它们与Bl细胞抗原受体结合后,B1细胞由于受体交联而活化。

阅读理解

Do you know something about the holiday camps in Hong Kong? The students in Hong Kong used to take part in an English holiday camp in their holidays. And their parents weren’t with them. Though they were very young.

Now they still enjoy taking part in many kinds of holiday camps without their parents. Many parents let their children take part in some kinds of holiday camps in order to learn some practical knowledge in their life. And also learn some knowledge about living skills, science, reading and writing... The most important for the children is to learn to look after themselves.

Holiday camps in Hong Kong are not so expensive. Most of the families can afford to send their children there for further study, for making their bodies strong... And the government never charges (收费) for them.

It is said that students in Hong Kong have much knowledge about many things. Perhaps it has something with the kinds of holiday camps.

小题1:Students in Hong Kong like to take part in the _________.

A.holiday camps

B.English holiday camps

C.science holiday camps

D.Chinese holiday camps小题2:The most important thing for the students to take part in the holiday camps in Hong Kong is _________.

A.to make their bodies strong

B.to learn much knowledge about many things

C.to learn to look after themselves

D.to have a further study about many subjects小题3:The cost to take part in a holiday camp is _________.

A. very dear       B not cheap        C. very high       D. low

小题4:The students who often take part in the holiday camps _________.

A.must have much knowledge about many things

B.must he very thin

C.must he very tall

D.must be very beautiful

多项选择题