A few years later, McCafferty et al. structure analogous to a lock) located at the upper tips of the Y shaped antibody molecules. This paratope is usually specific for one particular epitope (analogous to a key), displayed on the particular antigen, allowing these two structures to specifically bind together. Thus, this mechanism could allow an antibody to tag a microbe as well as an infected cell to be attacked by other parts of the immune system and also to directly neutralize its target [1]. == 2. Recombinant Antibody Technology == Being a major part of the immune system, antibodies represent a powerful weapon system in defending KX2-391 our body against non-self-agents. But, to interact with as many foreign structures as you possibly can, an enormous quantity of different molecules, bearing different specificities, are needed. This diversity can be produced through somatic recombinant and hypermutagenesis of a set of variant genes [2]. During the past decade, improvements in recombinant antibody technology have greatly facilitated the genetic manipulation of antibody fragments [4,5]. The genetic manipulation of recombinant antibodies thus improved our understanding about the structure and functional business of immunoglobulins. Further, these improvements have led the development of a large variety of designed antibody molecules for research, diagnosis, and therapy with specificities out of reach of standard antibody technology. Once cloned, it is then possible to increase the affinity and specificity of antigen binding by mimicking somatic hypermutation during an immune response [6]. It may even be possible to replace the Muc1 existing practices of animal immunization and hybridoma development through a bacterial system capable of synthesizing and expressing practically unlimited quantities of antibodies to almost any antigen. Since 1975, Kohler and Milstein have launched the hybridoma technology which enabled a defined specificity of monoclonal antibodies to be produced in consistent quality as well as in large quantities in the laboratory. Since then, monoclonal antibodies (mAbs) have been favored as they can KX2-391 be produced in unlimited quantities to practically bind to any antigen and are more easily standardized [7,8]. Besides monoclonal antibodies, hybridoma cells that are successfully produced could then serve as a starting material in the generation of Fab, or Fv fragments in lymphoid or nonlymphoid cells [9]. Monoclonal antibodies face several difficulties, as they are almost exclusively murine in origin thus could produce human anti-mouse antibody (HAMA) when launched to human therefore limits their clinical applications [7,8]. Added to this, monoclonal antibody generating technology is very laborious and time consuming. Furthermore, small mammals like mice do not usually provide the high-affinity antibody response to particular antigen needed for sensitive assay development [10]. These limitations of traditional techniques have led several research groups to investigate the use of phage display in generating scFv antibodies. The first study in generating recombinant antibodies in bacteria was hampered due to improper folding and aggregation of the polypeptide in the bacterial cytoplasm [4,11]. In order to overcome these problems, Skerra and KX2-391 Plckthun [12] have launched a one-step-forward technology whereby only parts of the antibody molecule (Fab or Fv fragments) are used for expression purposes. The breakthrough for competentE. coliexpression of antibody fragments yet was brought by introducing several types of vectors (e.g., phagemid) to be used in the recombinant antibody construction. These vectors could offer soluble antibody secretion directly into the periplasm space by means of its oxidizing environment that contributes for the correct formation of disulphide bonds between the antibody domains [12,13]. Recently, the technology has been improved through recombinant DNA technology and antibody engineering whereby antibody genes can now be cloned and expressed successfully as a fragment in bacteria [12], on mammalian cell and yeast [15], plant [16], and also insect cells [17]. One advantage of this new technology is usually that they could retain the intact antigen binding site (paratope) while reducing the size of the antibody molecule. In comparison to the parental antibody, these minimized antibodies have several advantages in clinical practices including better tumor penetration, more rapid blood clearance, and lower retention occasions in nontarget tissue and also to reduced immunogenicity. It also could lead.
