Conversion of cardiac and liver transplant recipients from HPLC and FPIA (polyclonal) to an FPIA (monoclonal) technique for measurement of blood cyclosporin A

In an effort to replace HPLC and FPIA (polyclonal) for whole blood determination of Cyclosporin A (CsA), this study examined the application of FPIA (monoclonal) in patients post cardiac and liver transplantation. The assay had a minimum detectable dose of 15 microg/L, an overall recovery of 97% and was linear to 1200 microg/L, and gave inter-assay precision values of < 5% (CV). On comparing FPIA (monoclonal) and HPLC for 59 cardiac transplant recipient blood samples, a correlation of FPIA (monoclonal) = 1.30 (HPLC) + 36.34, r = 0.96 was obtained. With liver transplant samples (n = 348), the correlation was FPIA (monoclonal) = 1.21 (HPLC) + 42.15, r = 0.98. Correlation on 131 cardiac transplant recipients gave FPIA (monoclonal) = 0.31 FPIA (polyclonal) + 43.97, r = 0.68. It is concluded that when converting from HPLC to FPIA (monoclonal) a positive bias of 21%-30% is observed, and in replacing FPIA (polyclonal) with FPIA (monoclonal), a negative bias of 50%-69% is seen with liver and cardiac patients respectively. These data indicate that therapeutic ranges should be re-established or adjustments in CsA dosing would be necessary.

Evaluation of reference ranges for fatty acids in serum

Long chain fatty acid fractionation has become a valuable tool in the management of patients maintained on total parenteral nutrition. While many clinicians prefer to use absolute concentrations to monitor a patient's fatty acid status, reference ranges are not available. Previous reference range studies reported values in terms of percentages only and calculated ranges parametrically. However, due to the non-Gaussian distributions of some serum fatty acids, it is necessary to calculate reference ranges non-parametrically. Serum from blood donors (n = 130) were collected and analyzed for total fatty acids by gas-liquid chromatography. Results for each of the fatty acids were calculated both as a concentration and as a percentage of the total fatty acids measured.

Whole-blood cyclosporin G in renal transplant recipients determined by two immunoassays and liquid chromatography

Cyclosporin G (CsG) is less nephrotoxic than cyclosporin A (CsA) and is undergoing clinical trials for use as an immunosuppressive agent after renal transplantation. Three assays for whole-blood CsA-HPLC, RIA (INCSTAR, Cyclo-Trac SP), and FPIA (Abbott TDx)--were adapted for use with CsG and were assessed for analytical suitability and to determine which assay was capable of deriving CsG values rapidly after transplantation. The assays were acceptable in terms of sensitivity, linearity, analytical recovery, and precision. When considering blood samples (n = 107) from renal transplant recipients receiving a low dose of CsG (5 mg/kg per day) and a high dose (10 mg/kg per day), we obtained the following correlation data: RIA = 0.974HPLC + 27.89 (r = 0.9798, Sy/x = 39.24); FPIA = 0.964HPLC + 33.59 (r = 0.9819, Sy/x = 36.66); and FPIA = 0.977RIA + 9.50 (r = 0.9894, Sy/x = 28.12). The FPIA of CsG is recommended as the most rapid method, although it is the most expensive. HPLC, RIA, and FPIA were capable of accurately deriving projected CsG concentrations at various stages of the clinical trial when the low- and high-dose regimes were tapered over a period of 16 weeks.

Whole-blood cyclosporin G in renal transplant recipients determined by two immunoassays and liquid chromatography

Cyclosporin G (CsG) is less nephrotoxic than cyclosporin A (CsA) and is undergoing clinical trials for use as an immunosuppressive agent after renal transplantation. Three assays for whole-blood CsA-HPLC, RIA (INCSTAR, Cyclo-Trac SP), and FPIA (Abbott TDx)--were adapted for use with CsG and were assessed for analytical suitability and to determine which assay was capable of deriving CsG values rapidly after transplantation. The assays were acceptable in terms of sensitivity, linearity, analytical recovery, and precision. When considering blood samples (n = 107) from renal transplant recipients receiving a low dose of CsG (5 mg/kg per day) and a high dose (10 mg/kg per day), we obtained the following correlation data: RIA = 0.974HPLC + 27.89 (r = 0.9798, Sy/x = 39.24); FPIA = 0.964HPLC + 33.59 (r = 0.9819, Sy/x = 36.66); and FPIA = 0.977RIA + 9.50 (r = 0.9894, Sy/x = 28.12). The FPIA of CsG is recommended as the most rapid method, although it is the most expensive. HPLC, RIA, and FPIA were capable of accurately deriving projected CsG concentrations at various stages of the clinical trial when the low- and high-dose regimes were tapered over a period of 16 weeks.

Measurement of cyclosporine by liquid chromatography and three immunoassays in blood from liver, cardiac, and renal transplant recipients

In an effort to replace HPLC for whole-blood determination of cyclosporine (CsA), we compared HPLC with radioimmunoassay (RIA; INCSTAR, Cyclo-Trac SP assay), fluorescence polarization immunoassay (FPIA; Abbott TDx), and in-house modified enzyme-multiplied immunoassay technique (EMIT; Syva Co.). For blood samples from 200 various transplant recipients, RIA = 1.262 (HPLC) - 8.16, r = 0.983; FPIA = 1.200 (HPLC) + 19.90, r = 0.981; and EMIT = 1.038 (HPLC) + 11.28, r = 0.985. For segregation by transplant type, RIA, FPIA, and EMIT demonstrated positive biases of 27%, 12%, and 3%, respectively, for liver transplant recipients (n = 50) when compared with HPLC. Heart transplant recipients (n = 50) gave positive bias values of 23%, 14%, and 4% for RIA, FPIA, and EMIT, respectively. Adult renal transplant recipients (n = 50) demonstrated positive bias values of 30%, 31%, and 0% for RIA, FPIA, and EMIT, respectively. For pediatric renal transplant recipients (n = 50), positive biases of 40%, 31%, and 9% were obtained for RIA, FPIA, and EMIT, respectively. We conclude that the modified EMIT represents the best replacement for HPLC.

Measurement of Cyclosporine by Liquid Chromatography and Three Immunoassays in Blood from Liver, Cardiac, and Renal Transplant Recipients

In an effort to replace HPLC for whole-blood determination of cyclosporine (CsA), we compared HPLC with radioimmunoassay (RIA; INCSTAR, Cyclo-Trac SP assay), fluorescence polarization immunoassay (FPIA; Abbott TDx), and in-house modified enzyme-multiplied immunoassay technique (EMIT; Syva Co.). For blood samples from 200 various transplant recipients, RIA = 1.262 (HPLC) - 8.16, r = 0.983; FPIA = 1.200 (HPLC) + 19.90, r = 0.981; and EMIT = 1.038 (HPLC) + 11.28, r = 0.985. For segregation by transplant type, RIA, FPIA, and EMIT demonstrated positive biases of 27%, 12%, and 3%, respectively, for liver transplant recipients (n = 50) when compared with HPLC. Heart transplant recipients (n = 50) gave positive bias values of 23%, 14%, and 4% for RIA, FPIA, and EMIT, respectively. Adult renal transplant recipients (n = 50) demonstrated positive bias values of 30%, 31%, and 0% for RIA, FPIA, and EMIT, respectively. For pediatric renal transplant recipients (n = 50), positive biases of 40%, 31%, and 9% were obtained for RIA, FPIA, and EMIT, respectively. We conclude that the modified EMIT represents the best replacement for HPLC.

Are clinical laboratory proficiency tests as good as they can be?

Present proficiency test services that use the peer group mean and statistically derived ranges of acceptability are not serving us optimally and are even counterproductive in some respects. We recommend that the target value be determined by a widely accepted reference method and that acceptable ranges be based on criteria related to clinical need. This approach was adopted several years ago in Germany and has already eliminated the use of several unsatisfactory analytical methods. Because the transition would probably take many years, we propose an interim solution to allow instrument manufacturers and laboratorians to adapt to these changes. The current peer group means and acceptable ranges should be supplemented by reference method values and acceptable ranges, based on clinical need, so that manufacturers and laboratorians can judge their performance against these new criteria and make the necessary adjustment in instrumentation and methodology. These processes should be paralleled by efforts to produce proficiency test materials that will not exhibit the matrix problems of present-day preparations.

Are Clinical Laboratory Proficiency Tests as good as They Can Be?

Present proficiency test services that use the peer group mean and statistically derived ranges of acceptability are not serving us optimally and are even counterproductive in some respects. We recommend that the target value be determined by a widely accepted reference method and that acceptable ranges be based on criteria related to clinical need. This approach was adopted several years ago in Germany and has already eliminated the use of several unsatisfactory analytical methods. Because the transition would probably take many years, we propose an interim solution to allow instrument manufacturers and laboratorians to adapt to these changes. The current peer group means and acceptable ranges should be supplemented by reference method values and acceptable ranges, based on clinical need, so that manufacturers and laboratorians can judge their performance against these new criteria and make the necessary adjustment in instrumentation and methodology. These processes should be paralleled by efforts to produce proficiency test materials that will not exhibit the matrix problems of present-day preparations.

Prevalence of non-A,non-B hepatitis/hepatitis C virus antibody in human immunoglobulins

Human intravenous immunoglobulins prepared by the cold ethanol fractionation technique of Cohn are considered safe with respect to infectivity. However, there have been several instances of transmission of both hepatitis B and non-A,non-B hepatitis viruses after administration of intravenous immunoglobulins. To determine the prevalence of hepatitis C virus antibody in intravenous immunoglobulins and protein preparations, 30 commercially available products were tested. Using the Abbott enzyme immunoassay for hepatitis C virus antibody, 27 of 30 (90%) immunoglobulins tested positive. The Ortho immunoassay showed that 28 of 30 (93%) were positive, with one discordant result between the Ortho and Abbott assays. An antigen-blocking or neutralization test (Abbott) confirmed the results of the Ortho assay. Bovine, sheep, goat, and horse sera also were tested before and after isolation of animal immunoglobulins. All results on the animal sera were negative, indicating that the fractionation process did not produce false-positive results. The high prevalence rate of hepatitis C virus antibody in intravenous immunoglobulins has important implications for follow-up of recipients, selection of serum donors, and implementation of anti-hepatitis C virus testing.

Comparison of various methods for the enumeration of blood cells in urine

This study compared the use of conventional urine microscopy, the KOVA system, Neubauer hemacytometry, and the Yellow IRIS for the determination of white blood cell (WBC) and red blood cell (RBC) counts in urine samples. Both KOVA WBC and RBC counts correlated better with the IRIS counts than with conventional microscopy. KOVA WBC counts correlated with Neubauer hemacytometry to the same degree as they did with IRIS WBC counts. The RBC count correlation was fairly similar between KOVA, hemacytometry, and the conventional method. It was concluded that the KOVA system is a suitable replacement for conventional urine microscopy.

Creatine kinase MB measured by fluorometric enzyme immunoassay and immunochemiluminescence

Creatine kinase MB (CK-MB) was measured in serum by a fluorometric enzyme immunoassay on the Stratus analyzer and by an immunochemiluminometric assay using the Ciba Corning Magic Lite System. Both methods were standardized against purified CK-MB, with Stratus underestimating by 20 percent and Magic Lite overestimating by 28 percent. The assays proved sensitive and linear; however, at a CK-MB concentration of 7.0 micrograms per L, Stratus gave unacceptable inter-assay precision. No cross-reactivity was observed with CK-MM or CK-BB and elevated triglycerides, bilirubin, and hemoglobin did not interfere. Correlations with an immunoradiometric assay (Embria), using 522 samples, gave: Stratus = 0.999 (Embria) -3.3; r = 0.969, and Magic Lite = 1.225 (Embria) -3.03; r = 0.971. When using Magic Lite, results from 40 acute myocardial infarction (AMI) patients gave a mean CK-MB value of 93.8 micrograms per L (range: 9.2 to 428 micrograms per L) at the peak of enzyme release and a mean value of 69.6 micrograms per L (range: 6.7 to 319 micrograms per L) when using Stratus. Both methods proved to be highly sensitive and specific in the diagnosis of AMI; however, the need for standardization of CK-MB assays is stressed.

Prevalence of non-A, non-B hepatitis/hepatitis C virus antibody in laboratory quality-assurance sera

Quality-assurance sera (QAS) are prepared from pooled sera composed of thousands of individual donations. Previous studies documented that a substantial percentage of individual QAS test positive for viral disease markers, including antibodies to human immunodeficiency virus and to hepatitis B surface antigen. We tested 239 QAS from various proficiency programs and commercial sources to determine the prevalence of hepatitis C virus (HCV) antibody. We tested samples for anti-HCV by using an enzyme immunoassay (EIA; Abbott Labs.) and an enzyme-linked immunosorbent assay (ELISA; Ortho Diagnostics). We observed an overall positive rate of 49% by one or both assays in all categories of sera tested. In addition, we found a greater rate of positivity (58%) in proficiency program samples than in commercial samples (43%). We found discrepant results between the two assays for 15 of 239 samples (6%). In the discrepant samples, the EIA result was positive, whereas the ELISA result was negative. Anti-HCV positivity in QAS has important implications for laboratory personnel handling these samples.

Rapid liquid-chromatographic method for simultaneous determination of plasma prednisone, prednisolone, and cortisol in pediatric renal-transplant recipients

A rapid liquid-chromatographic method is described for simultaneously determining prednisone, prednisolone, and cortisol in plasma. Before chromatography, samples containing an internal standard (methylprednisolone) were extracted with use of Chem Elut (Analytichem) columns. After elution of the glucocorticosteroids, the eluates were dried and reconstituted in a mobile phase of tetrahydrofuran/water (25/75 by vol). Samples were injected onto a reversed-phase C18 column, and analysis time was 15.5 min. Measures of analytical performance were all acceptable, and the method was used to assess noncompliance in pediatric renal-transplant recipients who were receiving prednisone and cyclosporine. Of the 37 pediatric patients tested, five (13.5%) were identified as noncompliant. The method is simple, accurate, and precise, and other steroids and medications commonly given to transplant recipients do not interfere with it.

Rapid liquid-chromatographic method for simultaneous determination of plasma prednisone, prednisolone, and cortisol in pediatric renal-transplant recipients

A rapid liquid-chromatographic method is described for simultaneously determining prednisone, prednisolone, and cortisol in plasma. Before chromatography, samples containing an internal standard (methylprednisolone) were extracted with use of Chem Elut (Analytichem) columns. After elution of the glucocorticosteroids, the eluates were dried and reconstituted in a mobile phase of tetrahydrofuran/water (25/75 by vol). Samples were injected onto a reversed-phase C18 column, and analysis time was 15.5 min. Measures of analytical performance were all acceptable, and the method was used to assess noncompliance in pediatric renal-transplant recipients who were receiving prednisone and cyclosporine. Of the 37 pediatric patients tested, five (13.5%) were identified as noncompliant. The method is simple, accurate, and precise, and other steroids and medications commonly given to transplant recipients do not interfere with it.

Assessment of biological reagents for presence of human immunodeficiency virus-1 (HIV-1) antigens

We tested 122 biological reagents including laboratory quality assurance sera and therapeutic human immune serum globulin products using an immunoenzymometric assay (IEMA) for HIV-1 antigens. Biological reagents tested were 64 HIV-1 antibody non-reactive and 44 HIV-1 antibody reactive quality assurance samples, and 14 HIV-1 antibody reactive human immune serum globulins from 21 manufacturers. Twenty-one of these biological reagents were previously reported by us as Western blot reactive. All 122 samples tested were non-reactive for HIV-1 antigens. Low incidence of HIV-1 antigen in these biological reagents should not alter laboratory safety practices in which all samples are considered infectious. Use of HIV-1 antigen measurements, either alone or with HIV-1 antibody determinations does not increase the likelihood of detecting HIV-1 reactive samples.

Photodynamic therapy using rhodamine-123 as a new laser dye: biodistribution, metabolism and histology in New Zealand rabbits

Rhodamine-123 (Rh-123) has been tested recently as a new laser dye for photodynamic therapy of human tumors in vitro and in vivo. Prior to initiation of clinical studies of this technique, we evaluated the biodistribution, metabolism, and pathological changes of Rh-123 in rabbits after systemic, repetitive injections of the dye in escalating doses. At doses between 0.1 to 1 mg/kg of Rh-123 injected intramuscularly (IM) daily for 5 days, no local or systemic toxicity was observed during the 4 weeks of follow-up. The peak concentrations of Rh-123 in micrograms/g of tissue was distributed as follows: kidney (3.24) greater than heart (2.24) greater than spleen (1.77) greater than lung (0.61) greater than liver (0.38) greater than skin (0.30) greater than skeletal muscle (0.17) greater than genitals (0.13) greater than brain (0.04). The elimination of Rh-123 was very rapid, with the dye falling to 2.7% of peak concentration at 72 hours in the kidneys, and to undetectable levels at 240 hours postinjection in all organs, except the skin, which retained 3% of the peak level at 240 hours. The low toxicity and rapid metabolism of Rh-123 in this preclinical model suggests that the dye and Argon laser may represent an effective combination for treatment of superficial malignancies.

Evaluation of the Behring Nephelometer for detection of low level urinary albumin

Mildly increased urinary albumin excretion rates and concentrations, below the quantity normally detected by conventional urinary protein and albumin methods, have prognostic significance for the development of nephropathy in patients with diabetes mellitus. The authors evaluated the automated Behring Nephelometer using Behring reagents for the detection of low level urinary albumin. Within run coefficients of variation (CVs, N = 20) are 1.7%, 1.3%, and 2.4% at mean urinary albumin levels of 16, 70, and 217 mg/L, respectively. Between run CVs (N = 20) are 4.5%, 2.6%, and 4.4% at mean albumin levels of 19, 71, and 239 mg/L, respectively. The method is sensitive to 3 mg/L. Hemoglobin, immunoglobulins, bilirubin, urea, and radiographic contrast media beyond a few hours of injection show no significant interference at levels normally expected from clinical specimens. Analysis is unaffected by pH within the physiologic range. Most urine specimens are stable for at least eight days when refrigerated at 4 degrees C. Specimen centrifugation before analysis is essential to avoid a negative bias that occurs when analyzing uncentrifuged refrigerated samples. Preanalytical freezing produces results higher than those observed in fresh or refrigerated samples. The authors conclude that automated nephelometry using the Behring Nephelometer is a convenient, simple, and accurate technique for the determination of low level urinary albumin.

Treatment of Wilson's disease with triethylene tetramine hydrochloride (Trientine)

Penicillamine is the drug of choice for the treatment of Wilson's disease, whatever the stage of the illness. Toxic manifestations may preclude the use of this life-saving drug in some patients and discontinuation of penicillamine therapy usually leads to death. We report our experience with Trientine in seven patients, aged 13 to 33 years, with Wilson's disease who developed toxic manifestations with penicillamine that required discontinuation of therapy. These include two with nephrosis, one with neutropenia, two with thrombocytopenia, and one each with a SLE-like and a Henoch-Schonlein-like syndrome. The patients were treated for periods from 6 weeks to 16 years with a dose of 0.5 to 2 g/day. Trientine proved to be an effective alternative copper chelating agent in the treatment of Wilson's disease in patients with penicillamine-induced neutropenia, thrombocytopenia, SLE, and nephrosis. No serious untoward side effects were noted.

Human, rabbit, bovine, and porcine creatine kinase isoenzymes are glycoproteins

Human, rabbit, bovine, and porcine creatine kinase (CK) isoenzyme preparations were extensively purified by isoelectric focusing and high-performance liquid chromatography and tested for the presence of carbohydrate. In this study, all the CK isoenzymes demonstrated positive periodic acid-Schiff (PAS) reactions, indicating the presence of carbohydrate. It is concluded that CK is a glycoprotein as a carbohydrate, associated with the M subunit of human, rabbit, bovine, and porcine isoenzymes. Also, carbohydrate is an integral part of the B subunit of both rabbit brain and porcine heart CK. Loss of carbohydrate may be important in enzyme catabolism, yielding a pool of circulating modified CK protein that, to date, has remained undetected by traditional methods.

Clinical assessment of the Hitachi 736-30 chemistry analyzer

We assessed the Hitachi 736-30 as a possible replacement for the SMAC I and as a laboratory cost-saving measure. For 24 analytes, both intra- and interassay precisions were acceptable; they also had good measuring ranges. Essentially no interference from lipemia was observed, while minimal interference from bilirubin was demonstrated. Hemoglobin interfered in the measurement of 12 of the analytes. Correlation with the SMAC I, Demand, Astra-8, ACA, and Varian Atomic Absorption Spectrophotometer was found to be acceptable, except for chloride which showed poor correlation with SMAC I and Astra-8 (Hitachi = 0.888 [SMAC] + 11.102, r = 0.9652; Hitachi = 0.885 [Astra] + 10.264, r = 0.9136). The Hitachi 736-30 offers reagent and method flexibility, high volume capability, and "walk-away" operation.

Use of specimen turnaround time as a component of laboratory quality. A comparison of clinician expectations with laboratory performance

Quantitative laboratory quality measures include test accuracy and precision. To be useful, however, tests also must be available in a timely manner. The authors surveyed 757 University of California, Los Angeles, house officers (485-64% responded) regarding their expectations of laboratory test turnaround time for five test groups that are regularly offered both stat and routine. They compared expectations with actual laboratory performance by evaluating turnaround time for 42,414 consecutive laboratory requests received over two weeks. The authors' laboratory performed 45% of studied analytes stat. Median turnaround time was 44 minutes for stat and 119 minutes for routine tests, although variation exists by test group. The percentage of time their laboratory met median stat and routine turnaround time expectations varies by shift and work area. Timeliness of results often may be as important as accuracy and precision in assuring quality of care and cost-effective use of hospital services. Although the laboratory may not meet current housestaff turnaround time expectations, it is unclear whether laboratory performance is inadequate or housestaff expectations are unreasonable. Publicizing actual routine turnaround times may reduce the number of stat requests ordered if routine turnaround times are incorrectly perceived to be too slow. Reduction in stat test ordering may improve overall laboratory performance and turnaround time. The authors recommend that clinical pathologists and clinicians together develop turnaround time goals based on practicality, medical necessity, and clinician expectations.

Rhodamine-123 as a new laser dye: in vivo study of dye effects on murine metabolism, histology and ultrastructure

Rhodamine-123 (Rh-123) is a mitochondrial-specific dye that has recently proven to be an effective fluorochrome for photo-dynamic therapy of squamous carcinoma cells and melanomas with the Argon laser. Complete eradication of heterotransplanted human tumors in nude mice was possible if tumors were first "sensitized" to Rh-123 and then treated with the Argon laser. Prior to initiation of human testing of this technique, the toxicity and pathological changes in BALB/c mice were tested by an escalating dose schedule after systemic injection of Rh-123. Animals' body weight, blood chemistry, enzymes and organ evaluation for histology, and ultrastructural changes were analyzed for 3 weeks after injection with Rh-123. The results of this study demonstrate that Rh-123 has significant systemic toxicity in BALB/c mice injected at doses of 10 micrograms/g of body weight and above, manifested by chronic weight loss and elevation of muscle enzymes with death of the animals injected at doses higher than 50 micrograms/g of body weight. At doses of 1 micrograms/g of Rh-123, no local or systemic toxicity was observed even after a 3-week follow-up, suggesting that safe and effective tumor sensitization might be possible in humans at this concentration. The high effectiveness of this new technique of photodynamic therapy and the low toxicity of this dye in this preclinical model system suggests that Rh-123 and the Argon laser may represent a powerful new method for treatment of superficial malignancies.

Measurement of cyclosporine in plasma from patients with various transplants: HPLC radioimmunoassay with a specific monoclonal antibody compared

This study compares cyclosporin A (CsA) concentrations in plasma from patients receiving various transplants, as measured by HPLC and RIA with a monoclonal antibody for CsA and an 125I-labeled ligand. The RIA was restandardized with in-house standards because it overestimated CsA by an average of 23%. The RIA was sensitive to 2 micrograms/L, the standard curve was linear from 20 to 500 micrograms of CsA per liter, analytical recovery was 98%, and CVs were less than 8% for intra- and interassay precision. RIA (y) vs HPLC (x) for 283 plasma samples from 145 patients gave a slope = 1.1256, r = 0.979. When the results were segregated according to transplant type, CsA in liver and heart recipients was overestimated by RIA as compared with HPLC: slope = 1.202, r = 0.973 and slope = 1.1477, r = 0.983, respectively. Adult and pediatric CsA values were acceptable when RIA and HPLC were compared: slope = 1.0755, r = 0.977 and slope = 1.0563, r = 0.980, respectively. For six samples (four heart, two liver recipients) where HPLC and RIA values demonstrated wide discrepancies, repeat HPLC and analysis of eluate fractions gave CsA concentrations nearer values by the initial HPLC assay. We conclude that this RIA cannot be substituted for HPLC in the case of heart and liver recipients. The need for each laboratory to standardize the RIA is obvious.

Measurement of cyclosporine in plasma from patients with various transplants: HPLC radioimmunoassay with a specific monoclonal antibody compared

This study compares cyclosporin A (CsA) concentrations in plasma from patients receiving various transplants, as measured by HPLC and RIA with a monoclonal antibody for CsA and an 125I-labeled ligand. The RIA was restandardized with in-house standards because it overestimated CsA by an average of 23%. The RIA was sensitive to 2 micrograms/L, the standard curve was linear from 20 to 500 micrograms of CsA per liter, analytical recovery was 98%, and CVs were less than 8% for intra- and interassay precision. RIA (y) vs HPLC (x) for 283 plasma samples from 145 patients gave a slope = 1.1256, r = 0.979. When the results were segregated according to transplant type, CsA in liver and heart recipients was overestimated by RIA as compared with HPLC: slope = 1.202, r = 0.973 and slope = 1.1477, r = 0.983, respectively. Adult and pediatric CsA values were acceptable when RIA and HPLC were compared: slope = 1.0755, r = 0.977 and slope = 1.0563, r = 0.980, respectively. For six samples (four heart, two liver recipients) where HPLC and RIA values demonstrated wide discrepancies, repeat HPLC and analysis of eluate fractions gave CsA concentrations nearer values by the initial HPLC assay. We conclude that this RIA cannot be substituted for HPLC in the case of heart and liver recipients. The need for each laboratory to standardize the RIA is obvious.

Evaluation of stat and routine turnaround times as a component of laboratory quality

Quality assurance has been an essential part of clinical laboratory operations for more than two decades. Analytic precision and accuracy goals have been established, and laboratory performance is monitored periodically. For a laboratory test to be useful, it must be available in a timely manner. Expedience of result reporting has not, however, been routinely included among measures of laboratory quality. The authors evaluated stat and routine turnaround times for 42,414 requests on 24 clinical analytes over a 14-day period with the use of a personal computer. Median turnaround time is 1.70 times faster for stat than for routine tests. When examined by shift, average turnaround time is considerably faster for tests ordered stat than for tests ordered routinely during the day and evening shifts, when the work load is the greatest. The authors are now examining turnaround time as an indicator of quality laboratory performance and efficiency. Computer systems in many clinical laboratories already have the sophistication necessary to perform turnaround time analysis. The authors recommend that clinical laboratories begin to include timeliness of stat and routine result reporting as part of their quality assurance programs. Laboratories may also wish to investigate the usefulness of stat requests during slower shifts because these requests may interrupt the normal flow of specimens without expediting result reporting.

Standardization for four protein analytes with the Behring Nephelometer

Owing to the generally higher values observed in the initial establishment of immunoglobulins (Ig) G, A, and M assays with the Behring Nephelometer, we elected to verify five commercial protein calibrators. This initial verification was performed by standardizing the Behring Nephelometer with the World Health Organization (WHO) International Reference Preparation for Human Serum Immunoglobulins G, A, and M. The instrument was also standardized for immunoglobulins and transferrin with use of the Reference Preparation for Serum Proteins (RPSP II). Analytical recoveries of the commercial calibrators varied. Also, assigned protein concentrations in both the WHO and RPSP II preparations made them unacceptable to us as benchmark calibrators for the Behring Nephelometer. Individual proteins (IgG, IgA, IgM, and transferrin) were obtained and primary standards prepared. Both transferrin and IgG were successfully standardized. However, IgA and IgM primary standards lacked 100% antigenicity, requiring removal of nonreactive IgA and IgM or reassignment of the correct value. The problem remains to find appropriate purified materials for IgA and IgM standardization.

Presence of HTLV-III antibodies in immune serum globulin preparations

The authors tested 15 immune serum globulin pharmaceutical preparations for antibody reactivity to human T cell lymphotrophic virus type III (HTLV-III) by the Abbott immunoenzymometric assay (IEMA). Although no evidence of HTLV-III infectivity has appeared after injection of similar preparations into humans, the authors found all samples IEMA reactive. Upon dilution, the authors demonstrated parallel decreases of antibody reactivity among two samples of gamma globulin, the Abbott-positive control, and a markedly reactive patient specimen. Gamma globulin isolated from sera of six animal species was nonreactive in the Abbott assay. All samples were nonreactive with the H-9 cell line antigen. Antibody reactivity to HTLV-III was confirmed in 13 of 15 gamma globulin samples when tested by the Electro-Nucleonics IEMA, and 14 samples contained at least the p24 band on Western blot analysis. Although false positivity occurs in IEMA assays possibly because of elevated protein concentrations and nonspecific binding, the authors, results show that in most circumstances immune serum globulin preparations tested do contain true reactivity to HTLV-III.

Influence of specimen treatment on nonreactive HTLV-III sera

We investigated effects of specimen treatment on HTLV-III antibody assay results. Freezing and thawing specimens 10 times did not increase specimen mean absorbance (A) values measured by the Abbott immunoenzymometric assay (IEMA). Heating blood donor serum specimens at 56 degrees C for at least 10 min inactivates virus, but converted 7.1% of nonreactive specimens to positive when measured by this IEMA. Also heating at 56 degrees C for 30 min increased A values of most specimens; however, the conversion to positive within assay ranged from 0 to 75%, with a mean of 17%. When 56 nonreactive patient specimens were heated, 55% became Abbott IEMA reactive, although ENI IEMA values did not increase and Western blot results remained nonreactive. Binding of immunoglobulins G and A to Abbott IEMA beads did not cause this conversion after heat treatment. We postulate that heating specimens causes alteration of some serum matrices and introduces nonspecific binding to assay bead antigen or antibody reagents. We recommend that for the Abbott IEMA, specimens may be stored frozen, and must not be heated to avoid altered reactivity.

Prevalence of antibodies to HTLV-III in quality-assurance sera

We tested 146 clinical-laboratory quality-assurance sera for antibodies to human T-lymphotropic virus III (HTLV-III). Of 127 human-based samples, 39 (31%) were positive by an immunoenzymometric assay (IEMA). Samples of human origin that gave IEMA reactivity included four of 10 ethylene glycol-based (liquid) samples, two of six in-house pools of fresh sera, and 32 of 111 lyophilized samples. All 19 bovine-based samples were negative. Antibodies to HTLV-III in 16 samples were remeasured by a second IEMA and the Western blot technique. All assays detected antibody reactivity in four of the 16 samples; however, results of the second IEMA and the Western blot agreed best. We report large discrepancies between assay results when laboratory reagents are tested for HTLV-III antibodies, and find that many quality-assurance samples containing human sera have measurable IEMA reactivity for HTLV-III antibody. Reactivity in these assays indicates the presence of antibody, not viral infectivity.

Prevalence of antibodies to HTLV-III in quality-assurance sera

We tested 146 clinical-laboratory quality-assurance sera for antibodies to human T-lymphotropic virus III (HTLV-III). Of 127 human-based samples, 39 (31%) were positive by an immunoenzymometric assay (IEMA). Samples of human origin that gave IEMA reactivity included four of 10 ethylene glycol-based (liquid) samples, two of six in-house pools of fresh sera, and 32 of 111 lyophilized samples. All 19 bovine-based samples were negative. Antibodies to HTLV-III in 16 samples were remeasured by a second IEMA and the Western blot technique. All assays detected antibody reactivity in four of the 16 samples; however, results of the second IEMA and the Western blot agreed best. We report large discrepancies between assay results when laboratory reagents are tested for HTLV-III antibodies, and find that many quality-assurance samples containing human sera have measurable IEMA reactivity for HTLV-III antibody. Reactivity in these assays indicates the presence of antibody, not viral infectivity.

Triclonal gammopathy in a patient with plasma cell dyscrasia

A triclonal gammopathy is an immunoglobulin abnormality in which three discrete monoclonal subpopulations of immunoglobulin molecules are present in a patient's serum. Monoclonal and biclonal gammopathies have been studied extensively, but relatively little is known about the much rarer triclonal gammopathies. The case described below illustrates some of the difficulties that this condition can present to the clinician and the clinical laboratory.

Triclonal gammopathy in a patient with plasma cell dyscrasia

A triclonal gammopathy is an immunoglobulin abnormality in which three discrete monoclonal subpopulations of immunoglobulin molecules are present in a patient's serum. Monoclonal and biclonal gammopathies have been studied extensively, but relatively little is known about the much rarer triclonal gammopathies. The case described below illustrates some of the difficulties that this condition can present to the clinician and the clinical laboratory.

Thyrotropin as measured by a sensitive immunoradiometric assay

An immunoradiometric assay (Boots-Celltech's "Sucrosep"; IRMA) for thyrotropin (TSH) was evaluated and results were compared with those of our in-house RIA procedure. The IRMA had a sensitivity of 0.02 milli-int. unit/L. In addition it displayed excellent intra- and inter-batch precision, cross-reacted negligibly with other pituitary hormones, and appeared to be relatively free of matrix effects (although deionized water did give an apparent TSH concentration of 0.13 milli-int. unit/L). Over the range 1.2 to 64 milli-int. units/L, correlation between the IRMA (y) and RIA (x) was excellent: y = 1.16x - 1.69 (r = 0.98). The normal reference interval for the IRMA was 0.4 to 4.2 milli-int. units/L. For patients suspected of hyperthyroidism who had been subjected to the thyroliberin test, the IRMA more effectively differentiated between euthyroidism and hyperthyroidism. During testing with thyroliberin, all nonresponding hyperthyroid patients had initial baseline TSH concentrations of less than 0.02 milli-int. unit/L by IRMA. This sensitive assay represents an important advance in the ability to differentiate between euthyroidism and hyperthyroidism.

Thyrotropin as measured by a sensitive immunoradiometric assay

An immunoradiometric assay (Boots-Celltech's "Sucrosep"; IRMA) for thyrotropin (TSH) was evaluated and results were compared with those of our in-house RIA procedure. The IRMA had a sensitivity of 0.02 milli-int. unit/L. In addition it displayed excellent intra- and inter-batch precision, cross-reacted negligibly with other pituitary hormones, and appeared to be relatively free of matrix effects (although deionized water did give an apparent TSH concentration of 0.13 milli-int. unit/L). Over the range 1.2 to 64 milli-int. units/L, correlation between the IRMA (y) and RIA (x) was excellent: y = 1.16x - 1.69 (r = 0.98). The normal reference interval for the IRMA was 0.4 to 4.2 milli-int. units/L. For patients suspected of hyperthyroidism who had been subjected to the thyroliberin test, the IRMA more effectively differentiated between euthyroidism and hyperthyroidism. During testing with thyroliberin, all nonresponding hyperthyroid patients had initial baseline TSH concentrations of less than 0.02 milli-int. unit/L by IRMA. This sensitive assay represents an important advance in the ability to differentiate between euthyroidism and hyperthyroidism.

Effect of arylsulfatase A and sialidase on the biochemical and immunological properties of creatine kinase isoenzyme BB

This work describes the action of the lysosomal enzymes arylsulfatase A (EC 3.1.6.1) and sialidase (EC 3.2.1.18) on human creatine kinase (CK, EC 2.7.3.2) isoenzyme BB. The isoenzyme, which gives a positive reaction with the periodic acid-Schiff reagent, contains 12 molecules of sulfate and two molecules of sialic acid per molecule. On treatment with arylsulfatase, CK-BB lost enzyme activity but retained immunoreactivity, its isoelectric point was altered, and it was partly bound to a "Glyco-gel" affinity column. On treatment with sialidase, the isoenzyme lost activity, its immunoreactivity was decreased by 70%, and the inactivated CK-BB would not bind to either "Glyco-gel" or concanavalin A. We propose that the sulfate groups are involved in maintaining the integrity of the active site of the enzyme but are not involved in antigenic recognition sites on the molecule. Sialic acid plays an important role in both the structural pattern of the antigenic determinant and the active site of CK-BB.

Effect of arylsulfatase A and sialidase on the biochemical and immunological properties of creatine kinase isoenzyme BB

This work describes the action of the lysosomal enzymes arylsulfatase A (EC 3.1.6.1) and sialidase (EC 3.2.1.18) on human creatine kinase (CK, EC 2.7.3.2) isoenzyme BB. The isoenzyme, which gives a positive reaction with the periodic acid-Schiff reagent, contains 12 molecules of sulfate and two molecules of sialic acid per molecule. On treatment with arylsulfatase, CK-BB lost enzyme activity but retained immunoreactivity, its isoelectric point was altered, and it was partly bound to a "Glyco-gel" affinity column. On treatment with sialidase, the isoenzyme lost activity, its immunoreactivity was decreased by 70%, and the inactivated CK-BB would not bind to either "Glyco-gel" or concanavalin A. We propose that the sulfate groups are involved in maintaining the integrity of the active site of the enzyme but are not involved in antigenic recognition sites on the molecule. Sialic acid plays an important role in both the structural pattern of the antigenic determinant and the active site of CK-BB.

The purification of human creatine kinase BB with high specific activity

This paper describes the purification of human creatine kinase BB with high specific activity (1,122 U/mg). The procedure used resulted in a protein yield of 5.4 mg (21% recovery) from 150 g of brain tissue. Two-dimensional electrophoresis and PAGE studies indicated that purified CK-BB might exist as native isoenzyme along with structural aggregates since the multi-banded appearance was reduced to a single band with sodium dodecyl sulfate treatment but not with 2-mercaptoethanol. Investigators are cautioned not to store brain tissue for prolonged periods of time before isolation of the isoenzyme as this may lead to protein redistribution with additional bands becoming evident on PAGE.