Thakur M L, DeFulvio J D
Thomas Jefferson University Hospital, Department of Radiation Oncology and Nuclear Medicine, Philadelphia, PA 19107.
J Immunol Methods. 1991 Mar 21;137(2):217-24. doi: 10.1016/0022-1759(91)90027-d.
Ascorbic acid incubated with monoclonal antibodies (22 degrees C, 60 min, pH 6.5) at a molar ratio of 3500:1, reduced 2.7 +/- 0.2% of the available disulfides to sulfhydryl groups that strongly bind 99mTc, and provided greater than 95% labeling efficiency for several IgM, IgG and F(ab')2 antibodies. The colloid formation was consistently less than 3% and the stability of the tracer when challenged with DTPA and cysteine was excellent. The immunospecificity of labeled antibodies as determined by immobilized specific antigen assay was 84 +/- 1% for IgM and 82.6 +/- 1.1% for IgG antibodies. For in vivo evaluation in mice bearing experimental abscesses and tumors, corresponding 125I-labeled antibodies served as controls. The liver uptake was similar (P = 0.76 and P = 0.12) for 99mTc or 125I labeled antinuclear antibody TNT-1 in mice bearing abscesses as well as for 99mTc-TNT-1-F(ab')2 and 125I-TNT-1-F(ab')2 in mice bearing tumors. Higher but statistically insignificant (P = 0.08, 0.18, and 0.73) urinary excretion was noted for 99mTc-antibodies. For corresponding 99mTc- and 125I-labeled antibodies, the abscess to muscle ratios (3.3 +/- 0.5 vs. 3.4 +/- 0.8) and tumor to muscle ratios (10.04 +/- 4.4 vs. 10.54 +/- 3.0) were similar. The high 99mTc-TNT-1-F(ab')2 uptake permitted excellent scintigraphic visualization of tumors whereas the nonspecific 99mTc-HSA did not (tumor/muscle ratio: 2.4 +/- 0.3). This method is simple, reliable, and adaptable to an instant labeling technique.
抗坏血酸与单克隆抗体在3500:1的摩尔比下孵育（22℃，60分钟，pH 6.5），可将2.7±0.2%的可用二硫键还原为能强烈结合99mTc的巯基，并为几种IgM、IgG和F(ab')2抗体提供大于95%的标记效率。胶体形成始终低于3%，并且当用二乙三胺五乙酸（DTPA）和半胱氨酸进行激发时，示踪剂的稳定性极佳。通过固定化特异性抗原测定法确定的标记抗体的免疫特异性，对于IgM抗体为84±1%，对于IgG抗体为82.6±1.1%。为了在患有实验性脓肿和肿瘤的小鼠体内进行评估，相应的125I标记抗体用作对照。在患有脓肿的小鼠中，99mTc或125I标记的抗核抗体TNT-1的肝脏摄取相似（P = 0.76和P = 0.12），在患有肿瘤的小鼠中，99mTc-TNT-1-F(ab')2和125I-TNT-1-F(ab')2的肝脏摄取也相似。99mTc标记的抗体的尿液排泄较高，但无统计学意义（P = 0.08、0.18和0.73）。对于相应的99mTc和125I标记的抗体，脓肿与肌肉的比值（3.3±0.5对3.4±0.8）和肿瘤与肌肉的比值（10.04±4.4对10.54±3.0）相似。99mTc-TNT-1-F(ab')2的高摄取使得肿瘤的闪烁显像极佳，而非特异性的99mTc-人血清白蛋白（HSA）则不然（肿瘤/肌肉比值：2.4±0.3）。该方法简单、可靠，且适用于即时标记技术。
