Nonspecific Monoclonal Antibody Research Articles

Reversal of multidrug resistance in human colon cancer cells expressing the human MDR1 gene by liposomes in combination with monoclonal antibody or verapamil.

Colorectal cancer is a major cause of cancer-related mortality in the world and the second leading cause of neoplastic death in the United States. A major obstacle in the chemotherapy of this neoplasm is the emergence of multidrug resistance that is frequently associated with the expression of P-glycoprotein (p170) encoded by MDR1 (also known as PGY1) genes. Previously, we demonstrated that liposome-encapsulated doxorubicin is more cytotoxic than free doxorubicin in human promyelocytic leukemia and human breast cancer cells with the multidrug-resistant phenotype. Our purpose was to investigate modulation of multidrug resistance by liposome-encapsulated vincristine (VCR) in a drug-resistant human colon cancer cell line HT-29mdr1 and the potentiation of this modulation in combination with monoclonal antibody MRK-16 or verapamil. HT-29 parental cells and HT-29mdr1 cells were exposed to free VCR or liposome-encapsulated VCR alone or in combination with MRK-16 or verapamil. Cytotoxicity of cells after various treatments was determined by neutral red staining, and cellular content of VCR was measured by using radiolabeled VCR; p170 expression of cells was assessed by azidopine. HT-29mdr1 cells express a high amount of p170, thus conferring sixfold to sevenfold resistance to VCR compared with the parent cell line. Liposome-encapsulated VCR lowers drug resistance in HT-29mdr1 cells fourfold; IC50 values (concentration that causes 50% reduction in cell number) were 12.5 +/- 2.5 ng/mL compared with 42.5 +/- 5.0 ng/mL with free VCR. IC50 values for free VCR with empty liposomes were 25 +/- 1.25 ng/mL. The combination of MRK-16 and free VCR produced a twofold increase in cytotoxicity over free VCR in p170-expressing cells; the combination of MRK-16 and liposome-encapsulated VCR produced a 10-fold potentiation of cytotoxicity. toxicity. Nonspecific monoclonal antibody NR-LU-10 had no effect on cytotoxicity of HT-29mdr1 cells with free VCR or liposome-encapsulated VCR. The combination of 1.5 microM verapamil potentiated the cytotoxicity of free VCR ninefold to 10-fold, IC50 values reduced to 5.0 +/- 1.5 ng/mL, and in combination with liposome-encapsulated VCR, IC50 values reduced to 2.5 +/- 1.0 ng/mL, demonstrating a 15- to 17-fold potentiation of cytotoxicity. There were no significant differences in drug accumulation in HT-29mdr1 cells when treated with liposome-encapsulated VCR or free VCR. Liposomes inhibited the photoaffinity labeling of azidopine to p170 HT-29mdr1 cells. Liposome encapsulation of VCR effectively modulates multidrug resistance in human colon cancer cells and may become an important modality in treatment for colon cancers.

Labelled white blood cells

For imaging inflammation, white cells can be labelled with In-111 tropolonate or Tc-99m HMPAO, both of which are lipophilic complexes capable of penetrating etrating cell membranes. Mixed white cells are satisfactory for routine clinical use although in some circumstances, such as for quantitative studies, pure granulocytes are preferable. The normal distribution of labelled leukocytes includes the spleen, liver, bone marrow and lung. Although the extent of pulmonary uptake reflects labelling injury, it also reflects, with different kinetics, increased intravascular granulocyte transit time, which is encountered in several systemic inflammatory diseases. The clinical applications of labelled white cells include imaging soft tissue sepsis, imaging and quantification of inflammatory bowel disease and diagnosis of osteomyelitis. New agents for imaging inflammation are designed, in general, to target inflammationin vivo without the need for blood cell isolationin vitro. They include non-specific immunoglobulin (HIG) and monoclonal antibodies (mAbs) to granulocytes. mAbs to endothelium are also being developed but have not yet been tested in man.

Tumor cell kinetics using two labels and flow cytometry.

A flow cytometry based, single sampling method employing sequential bromodeoxyuridine (BrdUrd) and iododeoxyuridine (IdUrd) labeling with an intervening interval is examined. BrdUrd-specific and nonspecific monoclonal antibodies and flow cytometry are used to estimate the duration of DNA synthesis and the potential doubling time in tumor cell populations using a single sampling or biopsy. A correction for labeled, divided cells allows postlabel incubation intervals to exceed the length of the G2/M phase of the cell cycle. The method yields reliable results when tested in experimental tumor systems in vitro and in situ, as well as in nine human tumors labeled in situ. It uses a somewhat simpler analysis than the alternative relative movement method, requiring only labeling indices, rather than both a labeling index and relative movement, but doses require the administration of two, rather than one, label. It provides an independent verification of and a useful single sampling alternative to the relative movement method for the estimation of the length of S phase and, from this, the potential doubling time in experimental or clinical human tumors.

Intravesical administration of tumor-associated monoclonal antibody AUA1 in transitional cell carcinoma of the bladder: a study of biodistribution.

Forty-five patients known or suspected to have transitional cell carcinoma of the urinary bladder underwent intravesical administration of either AUA1 tumor-associated monoclonal antibody or 11.4.1. nonspecific monoclonal antibody. Antibodies were radiolabeled with iodine-131, diluted in 50 ml normal saline and remained in the bladder for up to 1 h. During cystoscopy or transurethral resection of the tumor, tissue samples were taken from normal and malignant areas and were counted for radioactivity in a gamma counter. Blood samples were also measured for radioactivity. Mean uptake of AUA1 at 2, 20, 40 and 60 h after administration (expressed as 10(3) x percentage of injected dose/gram of tissue) was: 1.77 +/- 3.2, 1.28 +/- 1.67, 0.72 +/- 0.94 and 0, respectively in the tumor and 0.79 +/- 0.83, 0.14 +/- 0.34, 0.033 +/- 0.06 and 0 in normal tissue. Mean uptake of 11.4.1 at 2 and 20 h was: 0.47 +/- 0.42 and 0.018 +/- 0.015, respectively, in tumor and 0.2 +/- 0.19 and 0.013 +/- 0.002 in normal samples. No remarkable radioactivity was found in blood samples. Conventional and immunoperoxidase staining were also performed. Mean uptake of AUA1 by the tumor increased as the degree of tumor differentiation decreased. Our findings indicate that intravesical administration of AUA1 results in selective immunolocalization of AUA1 in intermediate and high-grade transitional cell carcinoma. This may allow the development of a new method for bladder carcinoma treatment or prophylaxis against recurrence.

Localization of Sarcoma Xenografts in Nude Mice with Indium-111-Labeled Monoclonal Antibodies

A labeling method utilizing modified carbohydrate moieties in antibody heavy chains as radionucleotide binding sites was evaluated. Murine anti-sarcoma monoclonal antibody (MAb 19-24) was labeled with Indium-111 (111In) using this technique and subcutaneous human sarcoma xenografts were successfully localized in nude mice. A nonspecific monoclonal antibody BL-3 was used as a negative control. Tumor-to-blood ratios of radioactivity in the mice injected with 111Inlabeled MAb 19-24 were significantly (P < 0.05) higher than those obtained with nonspecific MAb BL-3. Calculations of percentage injected dose of radioactivity per gram tissue showed relatively high specific uptake of MAb 19-24 in sarcoma xenografts. Radioactivity cleared from the blood rapidly and hepatic uptake of 111In-labeled antibodies was found to be relatively low. Biodistribution studies in normal mice with 111In-labeled antibodies showed only blood pool activity with no significant concentration of activity into organs. Therefore, immunoreactivity of the antibodies was retained after 111In-labeling utilizing this new technique, allowing specific binding of radiolabeled MAb to tumor xenografts with relatively low hepatic uptake.

Comparison of radioimmunotherapy and external beam radiotherapy in colon cancer xenografts

Radioimmunotherapy and external beam radiotherapy were compared in a nude mouse human colon cancer model. Radioimmunotherapy was delivered by intraperitoneal injection of 90Y-labeled anticarcinoembryonic antigen monoclonal antibody (anti-CEA MAB). Single fraction external beam radiotherapy was delivered using a 60Co teletherapy unit. Control groups received saline, unlabeled anti-CEA monoclonal antibody and labeled nonspecific monoclonal antibody. Subcutaneous CEA-expressing LS174T human colon carcinoma tumors were measured over time. Tumor growth suppression was expressed as delay to reach 2g compared to saline controls. Unlabeled anti-CEA monoclonal antibody and labeled nonspecific monoclonal antibody had no effect. External beam radiotherapy of 300, 600, 1000 and 2000 cGy produced growth delays of 3, 12, 17, and 22 days, respectively. Radioimmunotherapy with 120 μCi, 175 μ.Ci, and 225 μCi resulted in growth delays of 20, 34, and 36 days. Estimated absorbed tumor dose was 1750 cGy in the 120 μCi group. Similar comparisons were done with the more radioresistant WiDr human colon carcinoma cell line. External beam radiotherapy doses of 400, 800, 1200, and 1600 cGy resulted in growth delays of 6, 21, 36 and 48 days, respectively. Radioimmunotherapy of 120 μCi and 175 μCi resulted in growth delays of 9 and 19 days, respectively. The 120 μCi dose delivered an estimated absorbed tumor dose of I080 cGy to WiDr tumors. In summary, for the radiosensitive LS 174T line, radioimmunotherapy produced biologic effects that were comparable to a similar dose of single fraction external beam radiotherapy. For the more radioresistant WiDr tumor, radioimmunotherapy produced a biologic effect which was less than a similar dose of single fraction external beam radiotherapy. These studies suggest that a tumor's response to radioimmunotherapy relative to that of external beam radiotherapy is, in part, dependent on tumor radiosensitivity and repair capacity.

Lack of effect of isradipine on cyclosporin pharmacokinetics.

The influence of isradipine as a long acting form (IcazR LP 5 mg) on cyclosporin pharmacokinetics was studied in six hypertensive renal transplant patients (mean age 37 yrs; mean body weight 62 kg). These patients received a mean daily cyclosporin dose of 307 mg in two equal intakes. Isradipine was orally administered once a day at a dose of 5 mg before the morning cyclosporin intake. Cyclosporin kinetics was assessed over a 0-12-h period, the day before (D-1) and 13 days (D+13) after isradipine treatment. Whole blood concentrations of cyclosporin were determined by radioimmunoassay (RIA) using the SandimmuneR-RIA kit (specific and non-specific monoclonal antibodies). Area under the blood concentration-time curve (AUC), the maximum blood concentration (Cmax) and the time to reach Cmax (Tmax) on D-1 and D+13 were not significantly different whatever the specificity of the RIA method. For example, the mean AUC +/- sd values were 5,247 +/- 2,255 (D-1) vs 5,317 +/- 1,675 (D+13) microgram.1(-1).h for the specific and 20,905 +/- 8,317 vs 19,327 +/- 5,758 microgram.1(-1).h for the non-specific determinations. Therefore, the pharmacokinetics of cyclosporin is not influenced by co-administration of isradipine at a therapeutic dosage. Moreover, the clinical results show that isradipine treatment was effective after 13 days administration (mean systolic blood pressure 132 vs 158 mm Hg, P < 0.05 and mean diastolic blood pressure 77 vs 93 mm Hg, P < 0.05 in supine position), and well tolerated throughout the study.(ABSTRACT TRUNCATED AT 250 WORDS)

Nonspecific Antibody Binding: Protocols to Control Background on Unfixed Tissue During Colloidal Gold Electron Immunocytochernistry

AbstractThis report compares methods to reduce nonspecific antibody binding to mucin during colloidal gold immunocytochemistry on unfixed tissue. Fresh normal human colon was dehydrated with ethanediol (inert dehydration) and directly embedded in low-acid glycol methacrylate. Thin sections were incubated with nonspecific mouse monoclonal antibody from the X63 cell line. The effectiveness of preincubation agents (skim milk, egg white, a protein-starch mixture, and sheep whole serum) and antibody diluent additives (Nonidet P-40, Tween-20, bovine serum albumin, and sodium chloride) in preventing nonspecific binding of antibodies was tested. In some experiments uranyl acetate and tannic acid were added to the ethanediol to give mild fixation. The lowest background levels were achieved by preincubation with either egg white or dried milk powder or, alternatively, the diluent additives, CHAPS (3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate), 0.5 M sodium chloride, Tween-20 or Nonidet P-40. Uranyl ac...

Lack of Effect of the Calcium Antagonist Isradipine on Cyclosporine Pharmacokinetics in Renal Transplant Patients

Hypertension has emerged as a frequent side effect in transplant recipients on effective doses of cyclosporine (CsA). To control hypertension in renal transplant patients, calcium channel blockers have been used; some of these, however, have been shown to cause significant increases in CsA levels. These findings point out that possible interactions of each calcium antagonist with CsA deserve investigation. We performed an open, placebo-controlled study in 12 stable renal transplant recipients to determine whether short-term isradipine influences CsA pharmacokinetics. All patients had mild to moderate hypertension and received triple immunosuppressive therapy with CsA, azathioprine, and prednisolone. Throughout a 4-week period of isradipine treatment, blood CsA levels (specific and nonspecific monoclonal antibodies) remained stable. The mean trough specific level was 121 +/- 14 micrograms/L following placebo, compared to 120 +/- 14 micrograms/L during isradipine. Corresponding non-specific values were 465 +/- 68 and 474 +/- 63 micrograms/L. Also, values for Cmax, AUC, and t1/2 were not significantly changed following 4 weeks of isradipine. Mean arterial pressure was significantly reduced at the end of the study. This study implies that isradipine does not influence CsA metabolism. Further studies should be carried out to determine its long-term effects on CsA pharmacokinetics and renal function in transplanted patients.

Immunorecognition of estrogen receptors by monoclonal antibody H222 in reproductive tissues of the red-sided garter snake

A study was conducted to determine if a monoclonal antibody (MAB), H222, prepared against human breast cancer estrogen receptors (ER) would recognize ER in the oviduct and liver of garter snakes (Thamnophis sirtalis parietalis). Using sucrose gradient analysis of antibody-ER complexes bound to [3H]estradiol we have determined that the MAB H222 binds to an ER in the cytosolic and nuclear extracts of snake tissues. The snake ER is not bound by nonspecific MABs in the sucrose gradient analysis. Further, the snake ER does not bind to other steroids, including a synthetic progestin, R5020, or the androgens 5 alpha dihydrotestosterone and R1881. The quantity of ER in the snake oviduct (200-700 fmol/mg DNA) is within an order of magnitude of that found in the oviduct of the nonhuman primate. These results suggest that the MAB H222 and 17 beta-estradiol bind to an ER in the snake that shares common properties with mammalian ER.

Imaging of systemic Candida albicans infections with a radioiodinated monoclonal antibody: Experimental study in the guinea pig

Guinea pigs intravenously infected with Candida albicans were scanned to evaluate the use of radioiodinated monoclonal antibodies (MAb) to fungal antigens for detecting tissue infection sites. A total of 18 infected and 8 uninfected animals were used. MAb and F(ab′) 2 fragments directed against cell wall glycoproteins of C. albicans were labeled with 131I. Another MAb directed against a Schistosoma mansoni glycoprotein was labeled with 125I and used as a nonspecific control. Radiolabeled MAbs were injected at a dose of 12.5 μg (500 kBq) per animal. Images were acquired 24 h later. Animals were then killed and the dissected organs were separately gamma-counted. The number of C. albicans colony forming units (cfu) per gram was determined in each organ. A clear relationship was found between the anatomic distributions of C. albicans and 131I. The biodistribution of 131I radioactivity associated with anti- Candida MAb was greater in infected animals than in healthy animals and increased with the number of cfu per g in each organ. The distribution was highly specific in animals with Candida endophthalmitis, a pathognomic feature of organ involvement during hematogenous dissemination. In contrast, the distribution of 125I radioactivity associated with the nonspecific MAb was similar in healthy and infected animals. In infected animals, it was totally independent of the intensity of fungal infection.

Assessment of immunosuppression by serum inhibition of alloreaction and measurement of cyclosporin A (CyA) serum levels in kidney graft recipients under CyA

The immunosuppressive effect of kidney graft recipient sera was studied on T-lymphocyte alloreactive line (4H) proliferation and compared to native cyclosporin A (CyA) and CyA metabolite concentrations determined by radioimmunoassay (RIA) using specific or nonspecific monoclonal antibodies. Three clinical groups were studied: (1) patients experiencing acute renal rejection episodes (CyA-R), (2) patients experiencing CyA-dependent nephrotoxicity episodes (CyA-TOX) and (3) patients in a clinically steady state (CyA-ST), according to their therapeutic regimen i.e., monotherapy (CyA alone) or polytherapy (CyA associated with prednisolone and/or azathioprine). Regardless of the clinical state, sera of patients in polytherapy displayed more inhibitory activity than those of monotherapy patients (24% and 40% inhibition of 4H proliferation, respectively, at sera dilution of 1:2), something which was no doubt due to the inhibitory activity of prednisolone on T-lymphocyte growth. In the two therapeutic regimens, CyA-ST patient sera exhibited the lowest inhibitory activity on the 4H line (45% and 65% inhibition of 4H proliferation in mono- and polytherapy, respectively, at sera dilution of 1:2). Sera from CyA-TOX patients were highly inhibitory (74% and 86% inhibition of 4H proliferation in mono- and polytherapy, respectively, at sera dilution of 1:2), in agreement with RIA assays showing increased native circulating CyA and CyA metabolites and daily CyA intake in this group as compared to CyA-ST. Surprisingly, CyA-R patient sera were no less inhibitory than those of CyA-ST patients on 4H-line, antigen-induced proliferation.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of low-dose prednisolone on cyclosporine pharmacokinetics in liver transplant recipients: radioimmunoassay with specific and non-specific monoclonal antibodies

The following study of cyclosporine pharmacokinetics was performed to investigate the effects of withdrawal of low-dose maintenance prednisolone (0.3-0.6 mg/kg body weight) from the routine immunosuppressive regimen given to 10 liver transplant recipients with stable liver function tests. After oral administration of cyclosporine (6.4-10.3 mg/kg) whole blood concentrations were measured by radioimmunoassay (RIA) with both a specific monoclonal antibody detecting parent drug and a non-specific antibody additionally detecting a cross-section of metabolites. Withdrawal of prednisolone produced no significant change in the mean time and concentration of maximum blood cyclosporine (3.3 h and 1160 micrograms/l, respectively), the initial and terminal elimination half-life (3.5 h and 18.4 h, respectively) and the area under the blood concentration versus time curve (AUC) measured with either the specific or non-specific monoclonal antibody. Measurements with these two antibodies indicated that the terminal elimination of cyclosporine metabolites was more rapid than for the parent drug (half-life: 14.5 vs 18.4, respectively).

Assessment of immunosuppression by serum inhibition of alloreaction and measurement of cyclosporin A (CyA) serum levels in kidney graft recipients under CyA

Abstract. The immunosuppressive effect of kidney graft recipient sera was studied on T-lymphocyte alloreactive line (4H) proliferation and compared to native cyclosporin A (CyA) and CyA metabolite concentrations determined by radioimmunoassay (RIA) using specific or nonspecific monoclonal antibodies. Three clinical groups were studied: (1) patients experiencing acute renal rejection episodes (CyA-R), (2) patients experiencing CyA-dependent nephrotoxicity episodes (CyA-TOX) and (3) patients in a clinically steady state (CyA-ST), according to their therapeutic regimen i. e., monotherapy (CyA alone) or polytherapy (CyA associated with prednisolone and/or azathioprine). Regardless of the clinical state, sera of patients in polytherapy displayed more inhibitory activity than those of monotherapy patients (24% and 40% inhibition of 4H proliferation, respectively, at sera dilution of 1:2), something which was no doubt due to the inhibitory activity of prednisolone on T-lymphocyte growth. In the two therapeutic regimens, CyA-ST patient sera exhibited the lowest inhibitory activity on the 4H line (45% and 65% inhibition of 4H proliferation in mono-and polytherapy, respectively, at sera dilution of 1:2). Sera from CyA-TOX patients were highly inhibitory (74% and 86% inhibition of 4H proliferation in mono-and polytherapy, respectively, at sera dilution of 1:2), in agreement with RIA assays showing increased native circulating CyA and CyA metabolites and daily CyA intake in this group as compared to CyA-ST. Surprisingly, CyA-R patient sera were no less inhibitory than those of CyA-ST patients on 4H-line, antigen-induced proliferation. This clinical group did not differ from others for CyA intake or level of circulating immunosuppressive molecules, suggesting that rejection could be associated with a state of interin-dividual variation in sensitivity to CyA. In addition, a polytherapeutic regimen seemed to modify CyA bioavailability in CyA-ST group patients, with a decreased CyA metabolite level as compared to their monotherapy counterparts (native CyA plus metabolite/native CyA ratio being 2. 73 and 3. 73, respectively). In contrast, in the CyA-R patient group, polytherapy appeared to be associated with an increase in CyA metabolite circulating levels (ratio 4. 79). In view of the low inhibitory activity of CyA metabolites, this profile might lead to rejection.

A radioreceptor assay for the measurement of cyclosporine activity: a preliminary report.

Cyclosporine A (CsA) is extensively metabolized in the liver. Some of the known metabolites share immunosuppressive properties with the parent drug. Furthermore, CsA therapy is used in an increasing number of clinical conditions, some of which affect the pharmacokinetics of the drug. At this time, it is not yet known if CsA or its metabolites are responsible for the nephrotoxicity or hepatotoxicity observed in some individuals. Some high-performance liquid chromatography (HPLC) and monoclonal immunoassay procedures measure parent drug and not the pharmacologically active metabolites, while polyclonal immunoassays and nonspecific monoclonal antibody immunoassays measure both parent drug and metabolites. However, it is unlikely that the degree of cross-reactivity with metabolites correlates with their immunosuppressive effect. To overcome these drawbacks, we have developed a method of measuring CsA activity in whole blood using specific receptors from the cytosol of human mononuclear leukocytes that have been semipurified through ultracentrifugation. The basis of the procedure is the competitive binding at specific receptor(s) between a constant concentration of [3H]dihydrocyclosporine and the variable concentrations of cyclosporine and its pharmacologically active metabolites in whole blood. Comparisons between six different assays (three specific, two nonspecific, and the receptor assay) were made. Overall, the two specific radioimmunoassay procedures correlated well to HPLC, while correlation of the two nonspecific immunoassay procedures to HPLC was poor. Poor correlation was also found to exist between the radioreceptor assay and the nonspecific assays, indicating that the cytosolic binding of CsA and its metabolites cannot be correlated to currently available assays.

Altered biodistribution of indium-111-labeled monoclonal antibody 96.5 to tumors and normal tissues of nude mice bearing human melanoma xenografts in visceral organs.

Human melanoma xenografts were produced in the subcutis, kidney, cecum and liver of different nude mice. An 111In-labeled anti-(human melanoma) monoclonal antibody (96.5) or an 111In-labeled nonspecific control monoclonal antibody (ZCE-025) was injected intravenously in separate groups of mice. Radioactive antibody accumulation was measured in tumor, blood, viscera, and carcasses. mAb 96.5 targeted specifically to tumor tissue regardless of site of growth. Tumors in the liver exhibited significantly (P less than 0.05) higher tumor-to-blood ratios (45 +/- 6, mean +/- SEM) than xenografts at other visceral organs, the lowest value being found for subcutaneous melanoma (2.6 +/- 0.5). The differences in tumor-to-blood ratio were due to significant alterations of antibody biodistribution, since the actual antibody concentration in the different tumor sites was similar. The percentage of recovered anti-melanoma antibody per milliliter of blood in mice with visceral lesions (4.6 +/- 1.1% ml) was significantly lower than that found in mice with subcutaneous tumors (9.5 +/- 1.4%/ml, P less than 0.05). Moreover, significantly higher levels (18.2 +/- 3.2%/g, 31.0 +/- 5.1%/g, respectively) of the melanoma mAb 96.5 were found in normal liver and spleen tissue recovered from mice with visceral tumors as compared to tissue from mice with subcutaneous tumors (9.2 +/- 0.9%/g, 13.5 +/- 1.9%/g, respectively; P less than 0.05). These results demonstrate that the presence of visceral tumor can significantly affect tumor-to-blood ratios, blood levels, and biodistribution of 111In-labeled mAb 96.5.

An explanation of the noncorrespondence between assessment methods of cyclosporin

Abstract. Various methods of determining cyclosporin (CyA) levels in patients after kidney transplantation were compared. These included polyclonal antibody (pcAb-), specific and nonspecific monoclonal antibody (S-and NmcAb-) radioimmu-noassays (RIA), and high performance liquid chromatography (HPLC). The results obtained by the various methods when compared showed some correlation but did not correspond. A probable explanation for part of this noncorrespondence is the presence of monodonaily crossreactive metabolites (CyA-M). Another reason was that the concentration of CyA in the standards supplied with the RIA kits was found to be higher than stated.

Analysis of monoclonal antibody uptake in tumours

Power (y = axb) and linear (y = a + bx) equations were derived, relating percentage uptake (y) of radionuclide tagged specific (SP) and non-specific (NSP) monoclonal antibody (MoAb) and blood flow (BF) to tumour weight (x) in animal models in the literature. Power equations were more significant than linear equations, that is, MoAb uptake and blood flow did not increase linearly with tumour weight. The power equations were similar to the equation relating surface area (SA) to the volume (V) of a sphere (SA = 4.84 V0.67), but with some categorical differences, namely aSP greater than aSA greater than aNSP, aBF and bSA greater than bNSP bBF.bSP was variable. These results can be correlated with tumour physiology. a and b for non-specific MoAb uptake were similar to those for blood flow, suggesting antibody uptake is blood-flow related. Tumours are vascularized from their surface, explaining their relationship to surface area. Autoradiographs show that the high aSP values are due to preferential uptake of specific MoAb by tumours.

Monoclonal antibodies against avian paramyxovirus-3: antigenic mapping and functional analysis of the haemagglutinin-neuraminidase protein and the characterization of nonspecific monoclonal antibodies

Sixteen monoclonal antibodies (Mabs) which immunoprecipitated the haemagglutinin neuraminidase (HN) of chorio-allantoic membrane-grown avian paramyxovirus-3 (PMV-3) of British turkeys were produced. Thirteen were PMV-3 specific. Three were nonspecific because they also bound to other viral proteins and to bovine kidney cells treated with neuraminidase enzyme or infected with influenza virus. The thirteen specific Mab defined four antigenic regions A-D by competition and variant selection assays. Region A was subdivided into five epitopes and region B into two epitopes. The thirteen Mab neutralized and were active in haemagglutination inhibition (HI) and twelve were active in haemolysis inhibition (HLI) tests. Neuraminidase inhibition (NI) was epitope-dependent. Mabs to five of the epitopes A1, A2, A3, A5, and C bound to the 1981 British turkey isolates but not the 1968 American turkey isolate. The Mab to epitope A4 bound to both viruses. The Mabs to epitopes B1, B2, and D also bound to a parakeet isolate of PMV-3 which was the third PMV-3 tested. The Mab to B2 gave identical titres to all three viruses and had HI, HLI, and NI activities. This made it a potential diagnostic reagent for avian PMV-3 viruses. One of the nonspecific Mabs bound to lactose-like moieties as reported on influenza virus and one to maltose-like moieties as on retroviruses. Immunoglobulin from all three nonspecific Mab had some HI activity.

Determination of cyclosporine concentrations with monoclonal antibodies.

We measured cyclosporine in whole blood from normal volunteers administered single oral doses of the drug and from two renal-transplant patients on immunosuppressive maintenance therapy, by liquid chromatography (I) and by radioimmunoassay with use of nonspecific polyclonal (II), specific monoclonal (III), and nonspecific monoclonal (IV) antibodies. Concentrations determined by III were equivalent to I, irrespective of cyclosporine dose, concentration, time after dose, or time after transplant. Concentrations determined by II and IV were consistently higher than those by I, owing to cross reactivity with metabolites. Ratios of values by II and IV to those by I increased from less than 1.5 to about 3-4 between 0.5 and 12 h after a single cyclosporine dose, owing to differences in rates of appearance and disappearance of cyclosporine and cross-reacting metabolites, though for the constant 12-h dose intervals in the two renal-transplant patients at steady state these ratios (most within the range 3-4) were relatively stable. Ratios of concentrations measured by IV to those by II (mean of 1.2 for single-dose data, most within the range of 1.2 to 1.5 at steady state) were unaffected by time after dose or time after transplant, suggesting that, despite certain cross-reactivity differences between the two nonspecific antibodies, results are proportional throughout therapy. We therefore propose that III and IV offer alternatives, respectively, to the currently used I and II for cyclosporine monitoring.