《生物技术药物》之抗体、疫苗与佐剂

抗体(单克隆抗体)

脾脏有上百万B淋巴细胞，具有合成不同的抗体能力。 当机体受抗原刺激时，抗原分子上的许多决定簇分别 激活各个具有不同基因的B细胞。被激活的B细胞分裂 增殖形成效应B细胞（浆细胞）和记忆B细胞，大量的 浆细胞克隆合成和分泌大量的抗体分子分布到血液、 体液中。如果能选出一个制造一种专一抗体的浆细胞 进行培养，就可得到由单细胞经分裂增殖而形成细胞 群，即单克隆。单克隆细胞将合成针对一种抗原决定 簇的抗体，称为单克隆抗体。

After obtaining either a media sample of cultured hybridomas or a sample of ascites fluid, the desired antibodies must be extracted. The contaminants in the cell culture sample would consist primarily of media components such as growth factors, hormones, and transferrins. In contrast, the in vivo sample is likely to have host antibodies, proteases, nucleases, nucleic acids, and viruses. In both cases, other secretions by the hybridomas such as cytokines may be present. There may also be bacterial contamination and, as a result, endotoxins that are secreted by the bacteria. Depending on the complexity of the media required in cell culture, and thus the contaminants in question, one method (in vivo or in vitro) may be preferable to the other.

This is possible because myeloma cells have lost the ability to synthesize hypoxanthine-guanine-phosphoribosyl transferase (HGPRT), an enzyme necessary for the salvage synthesis of nucleic acids. The absence of HGPRT is not a problem for these cells unless the de novo purine synthesis pathway is also disrupted. By exposing cells to aminopterin (a folic acid analogue, which inhibits dihydrofolate reductase, DHFR), they are unable to use the de novo pathway and become fully auxotrophic for nucleic acids requiring supplementation to survive.


This mixture of cells is then diluted and clones are grown from single parent cells on microtitre wells. The antibodies secreted by the different clones are then assayed for their ability to bind to the antigen (with a test such as ELISA or Antigen Microarray Assay) or immunodot blot. The most productive and stable clone is then selected for future use. The hybridomas can be grown indefinitely in a suitable cell culture medium. They can also be injected into mice (in the peritoneal cavity, surrounding the gut). There, they produce tumors secreting an led ascites fluid.
各论八
抗体、疫苗与佐剂

抗体：antibody

指机体的免疫系统在抗原刺激下，由B淋巴细胞或记忆细胞增殖 分化成的浆细胞所产生的、可与相应抗原发生特异性结合的免 疫球蛋白。 用微生物或其毒素、酶，人或动物的血清、细胞等制备的供预 防、诊断和治疗用的制剂。预防接种用的生物制品包括疫苗、 菌苗和类毒素。其中，由细菌制成的为菌苗；由病毒、立克次 体、螺旋体制成的为疫苗，有时也统称为疫苗。 佐剂是非特异性免疫增强剂，当与抗原一起注射或预先注入机 体时，可增强机体对抗原的免疫应答或改变免疫应答类型。



A membrane-bound form that is attached to the surface of a B cell and is referred to as the B cell receptor (BCR). The BCR is only found on the surface of B cells and facilitates the activation of these cells and their subsequent differentiation into either antibody factories called plasma cells, or memory B cells that will survive in the body and remember that same antigen so the B cells can respond faster upon future exposure. In most cases, interaction of the B cell with a T helper cell is necessary to produce full activation of the B cell and, therefore, antibody generation following antigen binding.


Monoclonal antibodies are typically made by fusing myeloma cells with the spleen cells from a mouse that has been immunized with the desired antigen. Polyethylene glycol is used to fuse adjacent plasma membranes, but the success rate is low so a selective medium in which only fused cells can grow is used.


The selective culture medium is called HAT medium because it contains hypoxanthine, aminopterin, and thymidine. This medium is selective for fused (hybridoma) cells. Unfused myeloma cells cannot grow because they lack HGPRT, and thus cannot replicate their DNA. Unfused spleen cells cannot grow indefinitely because of their limited life span. Only fused hybrid cells, referred to as hybridomas, are able to grow indefinitely in the media because the spleen cell partner supplies HGPRT and the myeloma partner has traits that make it immortal (similar to a cancer cell).

疫苗(vaccine)


佐剂(adjuvant)



An antibody (Ab), also known as an immunoglobulin (Ig), is a large Yshaped protein produced by B-cells that is used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. The antibody recognizes a unique part of the foreign target, called an antigen.[1][2] Each tip of the "Y" of an antibody contains a paratope (a structure analogous to a lock) that is specific for one particular epitope (similarly analogous to a key) on an antigen, allowing these two structures to bind together with precision. Antibodies are secreted by a type of white blood cell called a plasma cell. Antibodies can occur in two physical forms, a soluble form that is secreted from the cell, and a membrane-bound form that is attached to the surface of a B cell and is referred to as the B cell receptor (BCR).

Monoclonal antibodies (mAb or moAb) are monospecific antibodies that are the same because they are made by identical immune cells that are all clones of a unique parent cell, in contrast to polyclonal antibodies which are made from several different immune cells. Monoclonal antibodies have monovalent affinity, in that they bind to the same epitope.