Construction and selection of the natural immune Fab antibody phage display library from patients with colorectal cancer

AIM: To construct the natural immune Fab antibody phage display libraries of colorectal cancer and to select antibodies related with colorectal cancer. METHODS: Extract total RNA from tissue of local cancer metastasis lymph nodes of patients with colorectal cancer. RT-PCR was used to amplify the heavy chain Fd and light chain kappa and the amplification products were inserted successively into the vector pComb3 to construct the human libraries of Fab antibodies. They were then panned by phage display technology. By means of Dot immunoblotting and ELISA, the libraries were identified and the Fab phage antibodies binding with antigens of colorectal cancer were selected. RESULTS: The amplified fragments of Fd and kappa gained by RT-PCR were about 650 bp. Fd and kappa PCR products were subsequently inserted into the vector pComb3, resulting in a recombination rate of 40% and the volume of Fab phage display library reached 1.48 x 10(6).The libraries were enriched about 120-fold by 3 cycles of adsorption-elution-multiplication (panning). Dot immunoblotting showed Fab expressions on the phage libraries and ELISA showed 5 clones of Fab phage antibodies which had binding activities with antigens of colorectal cancer. CONCLUSION: The natural immune Fab antibody phage display libraries of colorectal cancer were constructed. They could be used to select the relative antibodies of colorectal cancer.

Pharmacokinetics of radioimmunotherapeutic agent of direct labeling mAb ^(188)Re-HAb18

AIM:To labed Anti-hepatoma monoclonal antibody(mAb) fragment HAb18 F(ab')_2 was labeled with 188 Re for the pharmacokinetic model of ^(188)Re-HAb18 F(ab')_2 and to evaluate its pharmacokinetic parameters in hepatoma- bearing nude mice. METHODS:HAb18 F(ab')_2 was directly labeled with ^(188)Re using 2-mercaptoethanol(2-ME)as reducing agents. Labeling efficiency and immunoreactivity of ^(188)Re-HAb18 F (ab')_2 were evaluated by Whatman 3MM paper chromatography and live cell assay,respectively. Biodistribution analysis was also conducted in nude mice bearing human hepatoma in which animals were sacrificed at different time points(1,4,18,24 and 24h)after ^(188)Re-HAb18 F(ab')_2 was injected through tail-vein into hepatoma-bearing nude mice.The blood and radioactivity of organs and mass were measured.The concentrations of ^(188)Re-HAb18 F(ab')_2 were evaluated with a pharrnacokinetic 3P97 software. RESULTS:The optimum labeling efficiency and immunoreactive fraction were 91.7% and 0.78%, respectively.The parameters of ^(188)Re-HAb18 F(ab')_2 were: T_(1/2),2.29h;Vd,1.49×10^(-9)L·Bq^(-1);AUC,20.49×10~9Bq·h· L^(-1);CL,0.45×10^(-3)L·h^(-1).^(188)Re-HAb18 F(ab')_2 could locate specially in hepatoma with high selective reactivity of HAb18 F(ab')_2.^(188)Re-HAbl8 F(ab')_2 was mainly eliminated by kidney.The maximal tumor to blood ratio was at 48h,and maximal tumor to liver ratio was at 18h. CONCLUTION:The pharmacokinetics of ^(188)Re-HAb18 F(ab')_2 fit a I-compartment model.^(188)Re-HAb18 F(ab')_2 can be uptaken selectively at the hepatoma site.