Evaluation of monoclonal antibodies to human plasma low density lipoproteins. A requirement for lipids to maintain antigenic structure

題名: Evaluation of monoclonal antibodies to human plasma low density lipoproteins. A requirement for lipids to maintain antigenic structure 作者: Patton JG;Alley MC;Mao SJT

貢獻者: Department of Biotechnology 日期: 1982-12

上傳時間: 2009-11-26T01:43:37Z 出版者: Asia University

摘要: Human plasma low density lipoproteins (LDL) are composed of

approximately 25% apoproteins and 75% lipids (w/w). Immunochemical properties of LDL were studied using monoclonal antibodies. BALB/c mice were immunized with LDL and the spleen cells from these mice were then fused with a non-immunoglobulin secreting myeloma cell line (F0). The clones producing desirable antibodies were selected to study the antigenic properties of LDL by enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay. First, it was found that the maximal binding of 125I-labeled LDL to polyvinyl chloride microtiter dishes was not temperature dependent. The binding affinity was high with a Ka value of approximately 1.9 X 10(10) M-1 while the monoclonal antibodies possessed an affinity to LDL of 5 X 10(8) M-1 which was 2 orders less than the affinity of LDL to the dishes. The former binding, once established, was irreversible as judged by a subsequent incubation with an excess of unlabeled LDL. The latter binding could be displaced by unlabeled LDL. Therefore, the ELISA technique offered a satisfactory approach to study the interaction between LDL and monoclonal

antibodies. Removal of lipids from bound LDL by organic extraction resulted in a 50% loss of immunoreactivity, suggesting that the lipids of LDL are important in maintaining the antigenic structure of LDL. Since the apoprotein of LDL also constitutes approximately 40% of the mass (w/w) of very low density lipoproteins (VLDL), the immunoreactivity of VLDL assessed by LDL-monoclonal antibodies was also carried out.

Removal of triglycerides from VLDL by lipoprotein lipase resulted in a substantial loss of immunoreactivity as determined by

radioimmunoassay. These findings are consistent with the concept that lipids play a role in maintaining the integrity of the antigenic structure of LDL