Radioimmunoimaging of lymphoma in mice with a two-step pretargeting strategy using biotinyled CD45 monoclonal antibody and (188)Re-avidin / 南方医科大学学报

<p><b>OBJECTIVE</b>To establish a two-step pretargeting approach to lymphoma radioimmunoimaging in mice using biotinynaled CD45 monoclonal antibody (McAb) and (188)Re-avidin in a tumor-bearing mouse model.</p><p><b>METHODS</b>Six Nod-Scid mice bearing lymphoma cell xenograft were randomized to receive either an intravenous injection of 50 µg/200 µL biotinyled CD45 McAb followed 24 h later by an intraperitoneal injection of 3.7 MBq (50 µg/100 µL) (188)Re-avidin (two-step pretargeting group), or a single intravenous injection of 3.7 MBq (100 µg/100 µL) (188)Re-CD45 McAb (control group). SPECT was performed at 0.5, 1, 6 and 23 h post-injection to characterize (188)Re isotope biodistribution. At 24 h pos-injection, the mice were sacrificed for measurement of radioactivity uptake in the tumor and normal tissues and calculation of the tumor-to-non-tumor (T/NT) ratios.</p><p><b>RESULTS</b>SPECT showed that the two-step pretargeting method resulted in a low radioactivity in the blood pool during the imaging and a concentrated radioactivity in the liver and spleen. The transplanted tumor began to be displayed at 1 h post-injection and was clearly displayed at 1-6 h; the images were clear even at 23 h. With the two-step pretargeting method, the radioactive uptake at 24 h post-injection were (1.34∓0.52)%, (6.77∓2.32)%, and (2.81∓1.25)% in the tumor, kidney and liver, respectively, with low radioactivity levels in other organs and high tumor/blood and tumor/muscle ratios (4.28∓0.82 and 8.00∓0.88, respectively). In the control group, SPECT revealed intense radioactivity in the liver, spleen, and kidneys with obscure display of the tumor; at 20 h, the radioactivity in the blood pool remained high but that in the tumor was low, and the tumor/blood and tumor/muscle ratios at 24 h were only 0.58∓0.06 and 3.21∓0.24, respectively.</p><p><b>CONCLUSION</b>Compared with (188)Re-CD45 McAb, the two-step pretargeting approach exhibits a good specificity in targeting lymphoma with an increased T/NT ratio in mice and allows early tumor display at 1 h post-injection.</p>

Preliminary radioimmunoimaging and biodistribution of ¹³¹iodine-labeled single-chain antibody fragment against progastrin-releasing peptide(₃₁₋₉₈) in small cell lung cancer xenografts / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Monoclonal antibodies (mAbs) such as DD3, raised against progastrin-releasing peptide(31-98) (ProGRP (31-98)) antigen, have been used to target small cell lung cancer (SCLC). However, as an intact mAb, DD3 is cleared slowly from the body, with an optimal radioimmunoimaging time of 72 hours. More recently, a single-chain antibody fragment has demonstrated reduced excretion time in blood and normal tissues and is increasingly used in diagnostic cancer research. Thereby, it potentially increases the radioimmunoimaging efficacy. However, there have been few studies with this antibody fragment. The aim of this study was to characterize the preliminary radioimmunoimaging and biodistribution of (131)I-anti-ProGRP(31-98) scFv in nude mice bearing SCLC xenografts.</p><p><b>METHODS</b>Anti-ProGRP(31-98) scFv was used to detect ProGRP expression by flow cytometry analysis and immunohistochemistry. (131)I-anti-ProGRP(31-98) scFv was injected intravenously into healthy Kunming mice and the percentage injected dose per gram (%ID/g) in various organs was calculated. Similarly, the %ID/g and tumor/non-tumor ratio in xenograft-bearing mice was calculated. After injection of (131)I-anti-ProGRP(31-98) scFv, treated mice were imaged at 1, 24, and 30 hours. Then the tumor/base ratios were calculated.</p><p><b>RESULTS</b>ProGRP was highly expressed in NCI-H446 cells and xenograft tissue. The metabolism of (131)I-anti-ProGRP(31-98) scFv in healthy mice was consistent with a first-order and two-compartment model; T1/2α and T1/2β were 10.2 minutes and 5 hours 18 minutes, respectively. The %ID/g of (131)I-anti-ProGRP(31-98) scFv in xenografts was much higher than in healthy tissues at 12 hours after injection, reaching a maximum of (5.38±0.92) %ID/g at 24 hours. Successful imaging of xenograft tissue was achieved as early as 1 hour post-injection and persisted until 30 hours, with 24 hours proving optimal.</p><p><b>CONCLUSION</b>(131)I-anti-ProGRP(31-98) scFv shows highly selective tumor uptake with low accumulation in normal tissues and rapid blood clearance, indicating that it could be a promising agent for SCLC radioimmunoimaging.</p>

Production and quality control of [67Ga]-DOTA-trastuzumab for radioimmunoscintigraphy

Breast cancer radioimmunoscintigraphy targeting HER2/neu expression is a growing field of work in nuclear medicine research. In this study, trastuzumab was successively labeled with [[67]Ga] GaCl3 after conjugation with DOTA-NHS-ester. The conjugates were purified by molecular filtration, the average number of DOTA conjugated per mAb was calculated and total concentration was determined by spectrophotometric method. DOTA-Trastuzumab was labeled with [67]Ga. Radiochemical purity, integrity of protein after radiolabeling and stability of [67]Ga-DOTA-Trastuzumab were determined followed by biodistribution studies in wild-type rats [30 +/- 5.5 micro Ci, 2, 4 and 24 h p.i.]. The radioimmunoconjugate was prepared with a radiochemical purity of higher than 95% [RTLC]. The average chelate to antibody ratio [c/a] for the conjugate used in this study was 5.8:1. The final compound was stable in presence of PBS at 37[degree sign]C and room temperature. The sample was showed to have similar patterns of migration in the gel electrophoresis similar to the native protein. The accumulation of the radiolabeled antibody in liver, spleen, kidney, heart and other tissues demonstrates. [67]Ga-DOTA-Trastuzumab was prepared as a surrogate for important clinically applicable radionuclides used in SPECT and PET including In-111 and Cu-64 as a model of radiolabeling. It is also a potential compound for molecular imaging of SPECT for diagnosis and treatment studies and follow-up of HER2 expression in oncology

Synthesis, characterization and biodistribution of novel amine thiophene [99m]Tc labeled complex

[99m]Tc-labeled amine thiophene ligand might be a potential candidate for brain imaging. The purpose was to investigate the uptake of a radiolabeled drug in the brain. In this study, a tetradentate amine-thiophene-dione ligand was synthesized by the reaction of thiophene-2-carboxaldehyde with ethane-1,2-diamine and reducing with NaBH4. The ligand system was characterized by elemental analysis, FTIR and [1]H NMR. Radiolabeling of the complex with [99m]Tc was performed by reducing with stannous ions. The radiochemical purity of the radiolabeled drug was determined by paper chromatography [PC] and instant thin layer chromatography [ITLC]. Bioevaluation of the [99m]Tc complex was studied in rabbits. The yield of the final product was 4.42 g [60%] and the characterization data confirmed the synthesis of the final product. The efficacy of radiolabeling was >98%. A significant uptake was observed in the brain which retained significantly up to 4h. The data indicate that the proposed system may be suitable for brain imaging in future clinical applications

Application of labeled radioimmunoimaging tracing in detecting pulmonary embolism in rabbits after bone cement perfusion and relevant treatment effects / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>During the process of bone cement joint replacement, some patients show a series of complications, such as a sudden drop in blood pressure or dyspnea. The cause of the complication is considered to be due to emboli caused by the femur prosthesis insertion. The purpose of the present study was to detect the pulmonary embolism in rabbits after bone cement perfusion by radioimmunoimaging, and to explore its protective measures.</p><p><b>METHODS</b>Forty rabbits, 2.5 - 3.0 kg weight, were randomly assigned to four groups, with ten rabbits in each group. Group I (no intervention): Bone cement perfusion was done after medullary cavity reaming and pressurizing. Group II (epinephrine hydrochloride intervention): The medullary cavity was rinsed with a 1:10 000 normal saline-diluted epinephrine hydrochloride solution followed by bone cement perfusion after medullary cavity reaming and pressurizing. Group III (fibrin sealant intervention): The medullary cavity was precoated with fibrin sealant followed by bone cement perfusion after medullary cavity reaming and pressurizing. Group IV (blank control group): The medullary cavity was not perfused with bone cement after reaming. In each group, the rabbits underwent femoral head resection and medullary cavity reaming. Before bone cement perfusion, 2 ml of developing tracer was injected through the ear vein. Radionuclide imaging was performed at 60, 120, and 180 minutes after bone cement perfusion, and the pulmonary radioactivity in vivo was measured. The rabbits were immediately sacrificed, and the pulmonary tissue was removed and its radioactivity was measured in vitro. Pulmonary tissue was then fixed and the pulmonary embolism and the associated pathological changes were observed.</p><p><b>RESULTS</b>The pulmonary radioactivity in vivo was measured at 60, 120, and 180 minutes after bone cement perfusion. The radioactivities of the four groups were 11.67 ± 2.16, 14.59 ± 2.92 and 18.43 ± 4.83 in group I; 8.37 ± 3.05, 10.35 ± 2.24 and 11.48 ± 2.96 in group II; 3.91 ± 1.19, 5.53 ± 2.95 and 7.25 ± 1.26 in group III; 1.04 ± 0.35, 1.14 ± 0.87 and 1.43 ± 0.97 in group IV. The radioactivities of groups I, II, III at 60, 120 and 180 minutes were significantly higher than group IV (P < 0.05). The pulmonary embolism could be detected. Pretreatment with epinephrine hydrochloride and fibrin sealant significantly decreased the pulmonary radioactivity in group II and group III, but it was still higher than in the group IV.</p><p><b>CONCLUSIONS</b>Radioimmunoimaging is an alternative method for the dynamic observation of rabbit pulmonary embolism after bone cement perfusion. Radioimmunoimaging is the optional way to evaluate the effect of pretreatment with epinephrine hydrochloride or fibrin sealant on pulmonary embolism after bone cement perfusion.</p>

Mechanism of cardiotoxicity associated with Herceptin using (131)I-Herceptin radioimmunoimaging / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the mechanism of cardiotoxicity associated with Herceptin.</p><p><b>METHODS</b>Herceptin was labeled with iodine-131 using the Iodogen method. Radioimmunoimaging was performed in 5 rabbits at 3 h to 5 days following (131)I-Herceptin injection to investigate the biodistribution of Herceptin. (131)I-Herceptin uptake in each organ or tissue relative to that in the muscular tissue (O/M ratio) was calculated and compared. On the fifth day following the injection, the organs including the heart, lung, liver and muscles were taken for measurement of the weight and radiocounts. HER2 expression was measured by immunohistochemistry in these organs and tissues.</p><p><b>RESULTS</b>The O/M ratio of the heart was significantly higher than that of the lung (P=0.032) and liver (P=0.019) at 3 h after Herceptin injection, but reduced significantly at 24 h (P=0.001). The uptake of (131)I-Herceptin in the myocardium was slightly higher that that in the muscle and intestine, but lower than that in the lung and spleen. HER2 expression showed no significant difference between the myocardium and the other tissues such as the liver, lung, and kidney (H=3.236, P=0.172).</p><p><b>CONCLUSION</b>Myocardium expresses low levels of HER2 and accumulates Herceptin no more than the other tissues.</p>

[Production and quality control of technetium-99m radiolabeled monoclonal antibody against colon cancer cells]

Binding a monoclonal antibody to tumor associated antigens is an effective method for cancer therapy because these agents can specifically target malignant cells. In fact, monoclonal antibodies are effective agents for diagnosis, grading and treatment of different kinds of cancers. In this research, a new monoclonal antibody against colon cancer cells was prepared and radiolabeling with technetium-99m evaluated. This research was done in three parts: preparation of hybridoma cell against colon cancer cell line [HT29], production of monoclonal antibody, determination of its characterizations and radiolabeling with technetium-99m. mAb-D2 is an IgG1 with affinity constant of 7.2x10[9] M[-1] which can recognize CEA in tumor cells. Radiolabeling showed that [99m]Tc-HYNIC-mAb-D2 complex is stable, immunoradioactive, and has a desirable biodistribution. In this study, we gained a new radiopharmaceutical that may be a good candidate for radioimmunoscintigraphy

Septal endocarditis, bone infection and severe leg ischemia detected in Tc-99m labelled monoclonal anti granulocyte scan

Patient 28 years old has continued to have a persistent fever (39.2°C), despite ten days treatment by specific antibiotics for bacterial endocarditis associated to a recent claudication of the right lower leg. The persistent fever has motivated a 99mTc-labelled monoclonal anti granulocyte scan which has showed an important uptake in the myocardial septum, and other infection locations in temporal bone and in right tibial arteries. Two days after, a nanocolloids-99mTc WBS showed no uptake in the heart area, a total absence of uptake of the nanocolloids in the bone marrow of right tibia b and cranial SPECT views confirmed the infectious site in the right temporal bone. New antibiotic strategy was adopted successfully associated with surgical amputation of the right lower leg.

new monoclonal antibody radiopharmaceutical for radioimmunoscintigraphy of breast cancer: direct labeling of antibody and its quality control

Radioimmunoscintigraphy [RIS] has found widespread clinical application in tumor diagnosis. The antibody [Ab] PR81 is a new murine anti-MUCl monoclonal antibody [MAb] against human breast carcinoma. In this study a very simple, rapid and efficient method for labeling of this MAb with [99m] Tc, particularly suitable for development of a [kit] is described. The reduction of Ab was performed with 2-mercaptoethanol [2-ME] at a molar ratio of 2000:1 [2-ME:MAb] and the reduced Ab was labeled with [99m] Tc via methylene diphosphonate [MDP] as a transchelator. The labeling efficiency which was determined by instant thin layer chromatography [ITLC] was 94.2% +/- 2.3. Radiocolloides measured by cellulose nitrate electrophoresis were 2.5% +/- 1.7. In vitro stability of the labeled product in human serum which was measured by gel filtration chromatography [FPLC] was 70% +/- 5.7 over 24 hr. The integrity of labeled MAb was checked by means of SDS-PAGE and no significant fragmentation was observed. The results of the cell-binding studies showed that both labeled and unlabeled PR81 were able to compete for binding to MCF 7 cells. Biodistribution studies were performed in normal BALB/c mice at 4 and 24 hrs post-injection and no important accumulation was observed in vital organs. These results show that the new radiopharmaceutical may be considered as a promising candidate for imaging of breast cancer

Detección radioinmunoguiada de perforación del tracto gastrointestinal Estudio experimental / Radioimmunogided detection of perforation of the gastrointestinal tract

Se presenta un estudio experimental que tiene por objetivo evaluar la sensibilidad y especificidad de la detección de solución de continuidad del tracto gastrointestinal con la utilización de partículas pesadas marcadas con Tecnecio 99. Se diseñó un estudio experimental prospectivo triple ciego, con un cálculo de tamaño de muestra teniendo en cuenta una sensibilidad y especificidad superiores al 95 por ciento, con un error alfa del 0.05 y una precisión de 0.05. Inicialmente se evaluaron 4 conejos de la raza Nueva Zelanda para determinar: el anestésico y la dosis a utilizar, la capacidad del estómago en mililitros; los tiempos promedios de tránsito gastrointestinal, la capacidad de la cavidad abdominal en mililitros y la biodistribución del radiofármaco (absorción gastrointestinal, diseminación y distribución hemática y eliminación renal). Se utilizaron 40 conejos de la raza Nueva Zelanda y se analizaron en tres estaciones de trabajo independientes, asignando aleatoriamente 20 conejos en cada grupo de estudio (perforados y no perforados). El radiofármaco utilizado fue Tecnecio 99 sulfuro coloidal > 100 nm, 2.5 mCi a 140 –Kev de energía preparado en una dilución de solución salina al 0.9 por ciento quedando una concentración de 0.0025 mCi por mililitro. El rastreo se realizó con una sonda gamma a 10X. El análisis estadístico se realizó con el programa Episet V:1 aplicando la prueba de Chi Cuadrado.Todos los 20 conejos que tenían disrupción del estómago, presentaron una prueba positiva para detección de radioactividad en el líquido peritoneal analizado con un valor promedio de 467 y un rango de 37 a 1748. En los 20 conejos restantes que no tenían perforación de la pared gástrica la prueba fue negativa.La sensibilidad de la metodología diagnóstica fue de 0.98 y la especificidad de 0.98 con un intervalo...

Adherence to imaging protocol and impact of training on the interpretation of CEA-Scan® (arcitumomab) imaging for colorectal cancer

Purpose: To determine if imaging with arcitumomab (immunoscintigraphy) is sensitive to technical and interpretative techniques that must be mastered in order to obtain reliable results. We studied the impact of training to reduce the learning curve. Methods: 1) Evaluate the performance of an experienced Nuclear Medicine Physicians (Team A) un-blinded with their initial series of patients, compared to the conclusions of Experts (Team B) blinded from any clinical information; 2) Training of Team A is by the expert team on image acquisition, processing and interpretation techniques as well as using all clinical information and anatomic studies for comparison; 3) Assess the performance of the Team A on a second series of patients. 4) Questionnaires were sent to 65 consecutive physicians trained by experts to determine if the learned techniques improved interpretation of immunoscintigrams. Results: Twenty three (23) patients with CRC were included, 13 pre and 10 for the post teaching phase with a total of 30 clinically confirmed lesions (pathologically proven or demonstrated on follow-up). The clinically confirmed lesions include: 8 primary, 12 pelvic recurrences and 10 metastatic sites. On the pre-teaching series, Team A correctly identified only 6/19 lesions (32 percent). On the post teaching series, Team A found 8/11 lesions (73 percent) including 4/5 pelvic recurrence (80 percent), all 3 primary lesions, and 1/3 metastasis which compares favorably to published results. To determine the effect of blinded reading of immunoscintigrams, Team B reviews the first 13 studies without any clinical information or CT for comparison. Team B found 10/19 lesions (53 percent) with 4 false positive. Questionnaires were mailed to 65 trained physicians (54 returned), 67 percent of responders found that training improved their results, 22 percent experienced mixed results and 11 percent did not notice any improvement. Conclusion: The lower than expected sensitivity by the blinde...

Nuclear Medicine in Oncology

Nuclear oncolgy is important in the diagnosis, staging, and long-term surveillance of a number of cancers. Over the past 10 years there has been an explosion of new radioisotopic tracers aimed at detecting, staging and eventually treating tumors. Clinicians and oncologists can now use specific radiolabeled metabolic tracers, monoclonal antibodies, and molecular probes based on the sequencing of the human genome. The current applications of positron emission tomography (PET) in oncology have included characterizing tumor lesions, differentiating recurrent disease from treatment effects, staging tumors, evaluating the extent of disease, and monitoring therapy. The future developments in medicine may use the unique capabilities of PET not only in diagnostic imaging but also in molecular medicine and genetics. Radioimmunoscintigraphy is a technique which uses radiolabeled antibodies to visualize tumors, taking advantage of antigens preferentially expressed by malignant tissue. However, the implementation of radiolabeled antibodies as "magic bullets" for detection and treatment of diseases such as cancer has required addressing several shortcomings of murine monoclonal antibodies. Genetic engineering provides a powerful approach for redesigning antibodies for use in oncologic applications in vivo. Recently, noninvasive molecular imaging has been developed. Most current molecular imaging strategies are "indirect" and involve the coupling of a "reporter gene" with a complementary "reporter probe". Imaging the level of probe accumulation provides indirect information related to the level of reporter gene expression. In this article, the author discuss the current status of PET, radioimmunoscintigraphy, gene imaging and receptor imaging with a brief review on nuclear oncology.

Preparation and radioimmunoimaging of a monoclonal antibody against human granulocytes / 中国实验血液学杂志

The aim of this research is to prepare a novel monoclonal antibody against granulocytes by the intraperitional routine procedure and evaluate the usefulness of (99)Tc(m) labelled anti-granulocyte monoclonal antibody (McAb) SZ-102 for the detection of experimental inflammatory areas in rabbits. It was characterized as IgG1 subclass by the double immunodiffusion analysis. The flow cytometry demonstrated that SZ-102 reacted selectively with human granulocytes, monocytes, and with their bone marrow precursors, while human lymphocytes, red blood cells and platelets remained negative. In addition, SZ-102 antigen was expressed on the macrophages of liver, lung, thymus, spleen and lymph node by immunohistochemical SP methods. It is suggested that McAb SZ-102 is mainly against granulocytes. SZ-102 was labelled with (99)Tc(m) using 2-iminothiolane modification McAb and (99)Tc(m) -glucoheptonate (GH) transchelation method. The experimental rabbit model of inflammatory areas was prepared,through injecting with (99)Tc(m)-SZ-102 by ear-edge vein, and then imaged by SPECT. (99)Tc(m) labelled murine IgG was used as a negative control. The inflammatory areas in rabbits were clearly imaged at 2 to 4 hour after injection of (99)Tc(m)-SZ-102, while the control group after injection of (99)Tc(m)-labeled murine IgG was negative. In conclusion, the McAb SZ-102 may be a potential agent for the diagnosis and localization of inflammatory areas of carcinomas and clinically concealed infectious diseases.

Tamizaje neonatal para hipotiroidismo congénito en poblaciones de alto y bajo riesgo de recién nacidos del área de influencia de la Universidad el Bosque / Neonatal screening for congenital hypothyroidism in high and low risk newborns from Universidad El Bosque influence area

El objetivo de esta investigación fue realizar tamizaje neonatal para detectar neonatos con Hipotiroidismo Congénito en el área de influencia de la Universidad el Bosque, confirmar el diagnóstico, iniciar tratamiento temprano y realizar seguimiento, previniendo las respectivas consecuencias. Se recolectaron datos de las historias clínicas y muestras de TSH en sangre total de talón en 2400 recién nacidos vivos, después de 24 horas de vida, desde noviembre de 1999 hasta junio de 2001 en neonatos de bajo riesgo y desde febrero de 2001 hasta febrero de 2002 en neonatos de alto riesgo. Se tomó con criterio de alto riesgo todo neonato que ingresara al área de recién nacidos. Se informó a los padres mediante visita y folleto de difusión. La muestra se procesó en el laboratorio de biología Molecular empleando la técnica microELISA tipo sándwich para TSH y RIA para T4 en los casos a confirmar y con punto de corte de 20 mUI/ml. Para el análisis estadístico de los resultados se utilizó SPSS versión 8.0 para Windows. Entre los resultados más sobresalientes está la prevalencia, de 2 en 2400 recién nacidos vivos, dato similar al descrito por la literatura. Se encontró dependencia estadísticamente significativa entre el tiempo de toma de la muestra y los valores de TSH en talón. No se encontró dependencia de los casos positivos de hipotiroidismo congénito primario y las poblaciones de alto y bajo riesgo neonatal. Como conclusión, es necesario implementar y ejecutar programas de tamizaje neonatal, teniendo en cuenta sus invaluables beneficios.

The investigation of bioadhesive property of carbomer 934 by gamma camera in vivo / 生物医学工程学杂志

To study bioadhesive property of carbomer 934 in dog alimentary tract, carbomer 934 and ethylcellulose were radiolabelled with technetium-99 m. The gastrointestinal emptying rate of these materials was measured by the technique of gamma scintiscan. The results showed that the empty rate of adhesive material (carbomer 934) was remarkably slower in dog alimentary tract compared to nonadhesive material (ethylcellulose). It is concluded that, in dog, the interaction between gastrointestinal mucus layer and adhesive material or nonadhesive material was significantly different. Carbomer 934 had stronger bioadhesive property in vivo than that of ethylcellulose.

Targetted localisation and imaging of a murine lymphoma using 131I-labelled monoclonal antibody.

In vivo tumor targetting with radiolabelled monoclonal antibodies is a promising approach for the diagnosis and therapy of tumors. A specific monoclonal antibody (mAb), DLAB was generated to the Dalton's lymphoma associated antigen (DLAA) from Haemophilus paragallinarum-induced spontaneous fusion. In order to study the tumor localisation and biodistribution properties of the monoclonal antibody, scintigraphic studies were performed using the radiolabelled DLAB. 131-labelled DLAB was administered intravenously into Swiss mice bearing Dalton's lymphoma and external scintiscanning was performed at different time intervals. Clear tumor images were obtained which revealed selective and specific uptake of radiolabel and the results were compared with biodistribution data. The radioiodinated monoclonal antibody showed fast tumor uptake which increased significantly to 14.6% injected dose (ID)/g at 12 hr post-injection. Enhanced blood clearance of radioactivity resulted in higher tumor/blood ratio of 5.96 at 48 hr. 131I-labelled DLAB resulted in selective and enhanced uptake of the radioactivity by the tumor compared to the non-specific antibody and the results suggest the potential use of spontaneous fusion for producing specific monoclonal antibodies for tumor detection and therapy.

Factors affecting chemistry of reduction-mediated 99mTc-labelling of monoclonal antibodies and polyclonal human immunoglobulins.

In developing a new method for preparing a radiopharmaceutical for clinical investigation, a thorough understanding of reaction stoichiometry is crucial in optimizing the labelling chemistry. Factors determining labelling efficiency of the 2-mercaptoethanol (2-ME)-mediated 99mTc-labelling of antibody molecules were elucidated using anti-tumor monoclonal antibodies of different IgG subclasses (i.e. IOR-CEA(IgG1), M170(IgG1), 3F8(IgG3) and EMD (IgG2a)) and polyclonal human immunoglobulins (Sandoglobulin). Antibodies which were sensitive to 2-ME reduction (i.e. required 500-1000 molar excess of 2-ME) could tag 99mTc with high efficiency since they possessed abundant reactive sites (i.e. sulfydryl groups) for 99mTc binding. Reduction sensitivity of antibodies was unlikely to be affected by IgG subclass and could be rated as follows: Sandoglobulin > IOR-CEA > 3F8 > M170 > EMD. Concentrations of the reduced antibodies for effective labelling appeared to be related to the reduction sensitivity, i.e. 0.2, 0.4 and 0.6 mg/ml were required for labelling of IOR-CEA, 3F8 and M170 respectively. In addition, susceptibility to 2-ME reduction seemed to reflect the rate of antibody labelling. For 2-ME resistant molecules, i.e. M170 and EMD, successful labelling could be achieved by using a slow 99mTc reducing agent such as SnCl2 instead of SnF2 which reacted more rapidly. Since 2-ME generates reactive sulfhydryl groups that are distal to antigen binding sites, the immunoreactivity of the modified antibody was not affected by the effect of reduction.

Valor diagnóstico de los anticuerpos anti-Ro (SS-A) en lupus eritematoso sistémico ANA positivo / Diagnostic value of anti-Ro(SS-A) antibodies in ANA-positive systemic lupus erythematosus

Objetivo: Definir la participación de los anticuerpos anti-Ro(SS-A) en las lesiones del lupus eritematoso sistémico (LES). Material y método: Se compararon características demográficas, clínicas y serológicas en 33 pacientes con LES positivos y negativos para los anticuerpos anti-Ro(SS-A). Los anticuerpos antinucleares totales (ANA) fueron determinados por inmunofluorescencia indirecta sobre cortes de hígado de rata; las especificidades antinucleares anti-Ro(SS-A), anti-Sm/RNP, anti-Scl-70, y anti-Jo-1 fueron evaluados por ensayos inmunoenzimáticos, y los anti-DNA de doble cadena (dc) por radioinmunoanálisis. También se determinó la presencia del factor reumatoide (FR, aglutinación de látex), y de los inmunocomplejos circulantes por los métodos de precipitación con polietilenglicol (ICC-PEG) y el inmunoenzimático en base a la unión de C1q (ICC-C1q). Resultados: Todos los pacientes resultaron positivos para los ANA y el 30.3 por ciento(10/33) fueron positivos para los anticuerpos anti-Ro(SS-A). La distribución de los anticuerpos anti-Ro(SS-A) no dependió de la edad, sexo y raza de los pacientes con LES. El daño renal histológico, las lesiones cutáneas, las citopenias hematológicas, la artritis y los síntomas neurológicos no mostraron asociación con la presencia de los anticuerpos anti-Ro(SS-A). Los anti-Ro(SS-A) tampoco resultaron indicativos de la actividad de la enfermedad lúpica. En el plano serólogico, se encontró correlación positiva entre los anticuerpos anti-Ro(SS-A) y las cifras de anticuerpos anti-DNAdc (t = -3.65 p< 0.01), y la presencia de ICC-PEG (x2 = 3.94 p< 0.05). Conclusiones: La relación encontrada entre los anticuerpos anti-Ro(SS-A) y los anti-DNAdc subraya el papel diagnóstico de los anti-Ro(SS-A) para el LES, aunque su presencia no se acompaña de caracteristicas clínicas distintivas del LES en pacientes ANA positivos.