Preliminary results of 99mTc-OKT3 scintigraphy in renal allograft diagnosis

Aim: The labeling of monoclonal antibodies is widely used for immunoscintigraphic diagnosis of different diseases. Technetium-99m is often considered to be the radionuclide of choice for reasons of cost, availability and imaging properties, in spite of its relatively short physical half-life. The murine monoclonal antibody OKT3 is an IgG2a directed against the CD3 antigen on peripheral blood lymphocytes. The use of this antibody is particularly effective in preventing or reversing rejection episodes in allograft transplants. Here we show the preliminary results of 99mTc-OKT3 scintigraphy in transplantation patients. Materials and Methods: Briefly, OKT3 (300μL) was incubated for 10 minutes with 2-Mercaptoethanol. Then, SnCl2 was added to the solution and the incubation continued for another 10 minutes. 10 mCi of 99mTc was dispensed and incubated for another 20 minutes. Filtration with Milipore 0,45μ to separate unbound 99mTc and colloid from 99mTc-OKT3 was followed. Total activity of final product was measured and a 5 mCi total dose was drawn for patient injection. 14 patients submitted to renal transplant were studied, totaling 15 scans. Anterior scans were obtained 1 and 3 h after injection. Results: The normal biodistribution was in liver, spleen and kidneys. 99mTc-OKT3 had increased uptake in allograft rejection and clearance in patients with normal renal function. Conclusion: These preliminary results show that 99mTc-OKT3 scans seems to be a promissory radiopharmaceutical to evaluate renal transplant. More studies are now in progress