DEVELOPMENT OF INSTANT KITS FOR 99MTc-LABELLING OF ANTI-CEA MONOCLONAL ANTIBODY AND HUMAN IMMUNOGLOBULINS FOR SCINTIGRAPHY.

Abstract

Simplicity and rapidity are highly desirable features in the development of ^99mTc-labelled radiopharmaceuticals. On the basis of 2-mercaptoethanol reduction, three instant kits were formulated for preparation of ^99mTc-labelled anti-CEA monoclonal antibody (IOR-CEA) used in the detection of colorectal cancers and ^99mTc-labelled immunoglobulins (Sandoglobulin and Venoglobulin) for imaging of infection / inflammation in musculoskeletal system. The kits were sterile and demonstrated to be pyrogen free and had a shelf life of at least 1 year. Efficient labelling (>95% efficiency) could be achieved in 15 min at room temperature. All radiolabelled products exhibited 4-hour biodistribution patterns similar to those reported in literatures, i.e high blood background owing to long half life of IgG in plasma and high renal uptake because of in vivo cysteine transchelation. IOR-CEA was more resistant to cysteine challenge than Sandoglobulin and Venoglobulin. This facilitated the abdominal imaging using IORCEA. While the high renal activity in associating with Sandoglobulin and Venoglobulin did not interfere with the investigation of extremities. The costs for kit preparation were 40 times cheaper than those from commercial sources.

The instant kits developed in this study permitted the expensive radioimmunoscintigraphy within the reach of developing countries like Thailand where per capita incomes are far below the global standard.