40 Recombinant antibodies Kinase Inhibitor Library for clinical therapeutic use in humans are expressed in low yields in mammalian cells, which accounts for their high cost. To cut costs, cPIPP was expressed as a periplasmic protein in tobacco leaves at a high yield of 20 mg of purified protein per Kg fresh tobacco leaves.41 Being given that it was expressed in endoplasmic reticulum of the leaves, plant-specific fucose and xylose residues were not loaded on the antibody.42 cPiPP had an affinity of 1.9 × 1010 m−1 for hCG. It was totally devoid of cross-reaction with hFSH and hTSH and had <5% cross-reaction with hLH. The antibody was fully competent to block hCG-induced gain

of uterine weight of immature mice in vivo and hCG-induced testosterone production by Leydig cells in vitro.40,41 Its efficacy was also tested in a human cell system. Placental villi cytotrophoblasts, isolated from placental villi of MTP cases, on culture in a medium containing anti-hCG antibodies failed to fuse into syncytium. Furthermore, the production of progesterone by the placental cells was fully blocked by cPiPP.26 These observations vouch for the suitability of cPiPP for use as a vacation contraceptive and for non-surgical termination of pregnancy. Choriocarcinoma trophoblast cells are known to make and secrete hCG.43,44 The cells carry receptors for hCG, by virtue of selleck monoclonal humanized antibody inhibitor which hCG

acts as an autocrine growth factor for these cells. Radio-iodinated PiPP bound to these cells in vitro. JEG cells administered to Nude mice form a cancerous implant. Injection of 131I-PiPP to such mice led to selective localization of radioactivity

at 3-mercaptopyruvate sulfurtransferase the tumor site, whereas the radioactivity of a similarly radio-iodinated non-relevant antibody is distributed randomly all over the body45 (Fig. 1a,b). The binding of the radio-iodinated PiPP to tumor cells is further confirmed by histioradiography (Fig. 1c). These studies clearly demonstrate the utility of the recombinant antibody for imaging and selective delivery of radiations to the tumor cells. It could be of particular utility for tracing of metastasis of such cancers. The curious phenomenon of cancer cells expressing hCG or its subunits has been discussed elsewhere in this article. We carried out studies on T-lymphoblastic leukemia MOLT-4 and lymphocytic leukemia U-937 cells, both available from ATCC. Both MOLT-4 and U-937 cells were bound with cPiPP. The binding as studied by flow cytometry was on the membranes and was specifically competed by authentic purified hCG.46 hCG was not picked up from other cells but was indeed synthesized by the cancer cells, as permeabilized MOLT-4 cells enabled the detection of the presence of hCG within the cells, to which the antibody permeating in the cells could bind. Incubation of MOLT-4 cells with anti-hCG antibodies did not however impair the viability and multiplication of these cells. Nor were the cells lysed by cPiPP in the presence of complement.