The Coulter Counter Model S Plus--the shape of things to come

The Coulter Counter Model S Plus is a 12 parameter haematological analyser designed for service use in haematology laboratories. Eight parameters are standard in current routine haematological practice; the seven parameters generated by the Model S and a platelet count. The method of platelet counting is unique. The remaining parameters are new and comprise the platelet-crit, the mean platelet volume and size distribution measurements for both platelets and red cells. A description of the instrument is given including differences from the Model S. The new parameters are discussed in detail. Instrument precision is assessed in terms of linearity, reproducibility, drift, carry-over and protein build-up. The results of all are impressive. Instrument accuracy is assessed in detail; white cell count, red cell count, haemoglobin concentration and mean corpuscular volume being compared with those values measured by the Model S; the Model S Plus haematocrit is compared with the microhaematocrit and platelet counts with those from the Thrombocounter C/Thrombofuge system. All correlations are very satisfactory. Normal values are defined for the new parameters. Instrument design and function are assessed and reagent consumption quoted. Cell control reagents have been evaluated. A realistic hourly throughput for the Model S Plus is 70-80 samples.

Protocol for evaluation of automated blood cell counters. International Committee for Standardization in Haematology (ICSH)

This protocol is proposed for the evaluation of automated blood cell counters to assess the performance, advantages and limitations of such instruments. It is based on the International Committee for Standardization in Haematology (ICSH) 'Protocol for type testing equipment and apparatus used for haematological analysis' (1978a) and the British Committee for Standardization in Haematology 'Guidelines for the evaluation of instruments used in haematology' (Shinton, England & Kennedy, 1982). The document has been prepared by the ICSH Panel on Cytometry after discussion with colleagues. This tentative protocol will be reviewed 1 year after publication, in accordance with the ICSH rules, before it is adopted as a definitive standard.

Assessment of the Coag-a-Pet Dual Channel in the routine haemostatic laboratory

The Coag-a-Pet Dual Channel is an instrument which automatically records coagulation test end-points utilizing a photo-optical clot detection system. The instrument and its operation are described in detail. The capability of the instrument to perform tests of oral anticoagulant control, basic coagulation profiles and one-stage factor assays is assessed. In terms of precision and accuracy, the instrument performs well in carrying out the one-stage prothrombin time, Thrombotest, activated partial thromboplastin time using an automated APTT reagent but not kaolin, and one-stage factor assays. The thrombin clotting time can not be measured on this instrument. The instrument is most suitable for batched repetitive tests, reducing observer error and improving laboratory efficiency.

Detecting Human CD34 + and CD34 - Hematopoietic Stem and Progenitor Cells Using a Sysmex Automated Hematology Analyzer

In clinical medicine, particularly in the newly developing stem cell therapies required to support the practice of regenerative medicine, the measurement of both CD34+ and CD34- hematopoietic stem cells (HSC)/hematopoietic progenitor cells (HPC) is important in obtaining more accurate information about the total HSC/HPC content in various stem/progenitor cell sources. We report the results of an investigation into methods of detecting CD34+ and CD34- HSC/HPC using the immature information (IMI) channel incorporated into the Sysmex XE-2100 and SE-9000 automated hematology analyzers. In this study, CD34+ and CD34- HSC/HPC were separated by immunologic methods and quantified by flow cytometry (FACScan) and IMI channel analysis. In addition, CD34-/CD133+ HSC were prepared by a sequential antibody-based positive selection strategy. These cells appeared in the same area as CD34+ cells in the IMI channel of the automated hematology analyzer. These findings confirmed that an automated hematology analyzer can be used to measure both CD34+ and CD34- HSC. These results may explain the difference in HSC/HPC counts sometimes observed between the automated hematology analyzer and flow cytometric methods for CD34+ measurement. The results of this study demonstrated the potential of automated cell counting methods for measuring HSC content in cellular products for both research and clinical applications.

International Council for Standardization in Haematology (ICSH) recommendations for "surrogate reference" method for the packed cell volume

The spun packed cell volume (PCV, hematocrit) is a key measurement on which are based hematology instrument calibration, reference range determination, and assignment of values to calibrators/controls. In 2001, the International Council for Standardization in Haematology (ICSH) recommended a Reference PCV method, which is fully traceable to the ICSH reference hemoglobin method. Because of its complexity, however, this method is impractical for occasional use in routine laboratories and is therefore intended primarily for use by manufacturers of capillary microhematocrit tubes, liquid calibrators, and multichannel analyzers. In response to the need for a simpler method--accessible to all routine laboratories--the ICSH offers this "Surrogate Reference" PCV procedure. It is traceable to the original ICSH Reference PCV method and is based on spun PCVs obtained using borosilicate capillary tubes with an already-known relationship to this reference procedure. This ICSH "Surrogate Reference" PCV method is substantially simpler, thus putting it within the reach of most routine hematology laboratories.

Icsh activities and Asia

The International Council for Standardization in Haematology (ICSH), an international organization promoting international agreement on hematological testing, is now restructuring to strengthen its activities. In Asia, a diversity of testing methods exists and the resulting testing levels make it difficult to compare test results internationally among Asian countries. Fortunately, the ICSH is considering regionalizing its organization to 5 sub-societies to increase its activity, and we have been able to establish a new society, ICSH-Asia, under the ICSH umbrella.

Evaluation of Sysmex UF-100 urine flow cytometer vs chamber counting of supravitally stained specimens and conventional bacterial cultures

We evaluated the Sysmex UF-100 urine flow cytometer (TOA Medical Electronics, Kobe, Japan) with 269 uncentrifuged urine specimens by comparing it with Sternheimer staining and particle counting in 1-microL disposable chambers with both brightfield and phase-contrast microscopy (the reference method). Results of routine test strip analysis, sediment microscopy (182 specimens), and bacterial culture (204 specimens) were also available. Detection of urinary WBCs and RBCs was highly reliable with the UF-100 compared with manual chamber counting (r = .98 and .88, respectively). Identification of bacteria was equal to that with visual microscopy of uncentrifuged specimens; sensitivity was 55%, and specificity 90%, compared with bacterial cultures at a cutoff of > 10(3) colony-forming units per milliliter. Renal damage was difficult to evaluate even with manual methods because of the low counts of renal tubular cells and casts; with standard manual Sternheimer-stained sediment analysis, sensitivity was 65% to 69% and specificity 66% to 91%, compared with the uncentrifuged chamber method at a cutoff of 3 and 10 particles per microliter, respectively. Renal damage was demonstrated with the UF-100 with a sensitivity of 26% to 69% and specificity 92% to 94%, compared with chamber counts. Automated urinalysis with the UF-100 urine flow cytometer offers considerable savings in time and labor. When high sensitivity is needed, visual microscopic review should be performed to detect renal disease.

Guidelines for organisation and management of external quality assessment using proficiency testing. Expert Panel on Cytometry of the International Council for Standardization in Haematology

This document is intended to assist towards the WHO objective that external quality assessment (EQA) schemes be established at national and/or regional levels world-wide. Quality assurance is defined as all steps taken by the director of a laboratory to ensure reliability of laboratory results and to increase accuracy, reproducibility and between-laboratory comparability. This includes the use of internal quality control procedures and participation in external quality assessment. Internal quality control provides the means for evaluation of analytic test results at the time of testing in order to decide whether they are reliable enough to be released to the requesting clinicians. EQA, on the other hand, refers to a system of retrospective and objective comparison of results from different laboratories by means of proficiency testing (PT) organised by an external agency. The main purpose is to establish between-laboratory and between-method (including between-instrument) comparability, and agreement with a reference standard where one exists. Internal quality control and EQA complement each other and must never be considered as alternatives.

In vitro stability of the reticulocyte count

A collaborative study was undertaken to investigate the effect of storage conditions on the measured reticulocyte count in venous blood samples. It was designed to cover variation in the three main determinants, namely time, temperature and anticoagulant. The aim was to determine the time for which samples could be stored for subsequent analysis for clinical purposes.

Discriminant analysis of macrocytic red cells

Laboratory classification of red cell disorders uses the red cell indices (MCV, MCH, MCHC, RDW) and information gleaned from microscopic evaluation of a blood film. Additional red cell information is now available using the H series of automated blood cell analysers (Ames Technicon Division of Bayer Diagnostics). This study involved the development of a discriminant rule which would differentiate between three causes of macrocytosis (vitamin B12/folate deficiency, alcohol excess/liver disease and a reticulocytosis) using the information available on Research Screen 1 and Report Screen 3 of the H*1 instrument (Report Screen 3 is a graphical display of the trimmed scattergram of red cell volume and red cell haemoglobin concentration and Research Screen 1 displays the associated numerical data). Three methods of analysis were assessed to define a suitable discriminant rule. The percentages of patients correctly classified by the three methods were: 92.1%, 82.0% and 89.2% for Methods 1, 2 and 3 respectively. Method 1 involved the application of quadratic discrimination to transformed variables and produced the best results. Although complex, it could easily be applied using the microprocessor capability of the average multiparameter haematology analyser.

The campus at the University of Maryland at Baltimore

The University of Maryland at Baltimore (UMAB) is an urban professional school campus. Its 36 acres include 39 buildings, both historic and new. The campus fabric is marked by diversity. The new facilities master plan was developed to reflect the strategic planning process for the campus. Design guidelines are intended to create a common theme while still encouraging each building to have a unique identity. The new Health Sciences Library/Information Services building will sit diagonally from Davidge Hall, built in 1812 and the symbolic center of the campus.

Evaluation of a prototype for a reference platelet counter

A semiautomated single channel aperture-impedance particle counter was developed as a prototype for a reference platelet count for assigning values to reference preparations used in automated blood cell counts. The instrument is equipped with sheath flow and an aperture orifice of 50 microns in diameter and 60 microns in length to eliminate non-axial flow and minimise coincidence errors. Use of fixed volume and red blood cell:platelet ratios obviate dilution errors. The counter was assessed in accordance with the International Committee for Standardization in Haematology protocol for evaluation of automated blood cell counters. The counter provided a high level of linearity and precision, accurate coincidence correction, controlled volume, stability and negligible carryover.

T4: T8-lymphocyte ratios in human bone marrow: the effect of sampling technique

Marrow aspirate and trephine biopsy T4 : T8-lymphocyte ratios were compared with peripheral blood values. To do this, a new technique for harvesting marrow cells from trephine biopsies is described. Results show that blood and trephine ratios did not overlap. Marrow aspirate ratios were intermediate suggesting that peripheral blood contamination was causing aspirate T4 : T8 ratios to be falsely elevated.

Cyclical neutropenia and T8 lymphocyte mediated stimulation of granulopoiesis

A 33-year-old female with cyclical neutropenia and a reciprocally cycling T8 (suppressor/cytotoxic) lymphocytosis was investigated. T8 lymphocytes ranged between 1.4 and 5.6 X 10(9)/l and a significant proportion (50-75%) were preactivated (1a+). Fc gamma receptors were detected in only a minority (7-10%). Functional studies on the lymphocytes indicated that despite their phenotype, little natural killer and reduced suppressor activities were present. Anti-granulocyte antibodies were not detectable in the serum. Production of colony stimulating activity (CSA) was assessed in the patient and control subjects' lymphocytes. Using a methylcellulose marrow culture system, the CSA production by the patient's lymphocytes was markedly increased compared with the control. Monoclonal antibody cytotoxic experiments confirmed that the T8 lymphocytes were responsible. As peaks of circulating T8 lymphocytes were synchronous with granulopoietic activity in the marrow, the above findings may represent a homeostatic mechanism which is attempting to compensate for an underlying stem cell defect.

The implications of assaying external quality control sera under 'special conditions'

Two identical series of Wellcome quality control specimens were analysed by different procedures. One series was entered into the laboratory in the same way as patients' specimens while the other was analysed under special favourable conditions. This involved assaying the samples in replicate in different batches, omitting transcription errors and outliers, and placing the sample in a position following a calibration standard or an internal control. It was found that a significantly higher position in overall league ranking was achieved by assaying the control under 'special conditions'.

Comparison of Channelyser and Model S Plus determined platelet size measurements

A comparison has been made between Coulter Counter ZBI/Channelyser C1000 derived platelet distribution width (PDW), mean platelet volume (MPV) and platelet crit (PCT) with similar measurements generated by the Coulter counter Model S Plus. Correlations of PDW and MPV from the two systems are poor; that for PCT is acceptable. The differing results can almost certainly be attributed to physical differences in the measurement systems.

Evaluation of a semi-automated platelet-counting system

Coulter Electronics Ltd have produced a semi-automated platelet-counting system. Platelet-rich plasma may be obtained either by tube sedimentation or by means of the Thrombo-fuge, the latter being an instrument designed to produce accelerated sedimentation. The instrument is linear over the entire range of platelet counts, and machine reproducibility is good. Comparison of machine-rated with visual counts satisfied statistical evaluation. The technique can be handled by one operator and platelet counts can be achieved at the rate of 30 per hour by both methods although individual counts on the Thrombo-fuge may be obtained in approximately one-quarter of the time required for tube sedimentation. The throughput using the Thrombo-fuge could certainly be doubled were two sample plates supplied. Few problems were encountered during the evaluation and most could be avoided by meticulous technique. Visual counts must be performed when the sample haematocrit is greater than 50%-Discrepant counts have been obtained in patients with white cell counts exceeding 50 X 10(9)/1 and in patients with giant platelets. ESR elevation for any reason does not lead to serious discrepancy in results. The incidence of platelet clumping due to the presence of platelet agglutinins and of microclot formation due to inadequate mixing is probably much higher than is commonly thought, and certainly peripheral blood film scrutiny should never be omitted in patients with low counts. Careful examination of peripheral blood films must be combined with instrument counting for some time lest further causes of discrepant counting emerge.

Pruritus as a presentation of myelomatosis

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An assessment of the clinical usefulness of plasma ribonuclease assays

The usefulness of plasma ribonuclease assays was studied in (i) patients with possible protein deficiency, (ii) patients with myelomatosis, (iii) patients with carcinoma of the breast. In each group, the major factor associated with elevation of plasma ribonuclease was impairment of renal function. The assay was therefore of little value in the assessment of patients with myelomatosis or carcinoma of the breast. However, in the patients with possible protein deficiency and normal renal function, an elevation of plasma ribonuclease is, in general, associated with a decrease in serum albumin, transferrin and cholinesterase. Plasma ribonuclease may therefore be a useful parameter in the assessment of protein nutritional status.

Inhibition of platelet release reaction by acetylsalicylic acid

The inhibitory potency and duration of action of single doses of aspirin B.P., claradin (a low sodium effervescent preparation of acetylsalicylic acid) and aloxiprin (an aluminium co-polymer of acetylsalicylic acid) on platelet release reaction induced by adenosine diphosphate (ADP) were studied in seventeen volunteers. Aspirin B.P. and claradin at 300 mg and 150 mg inhibited release reaction in all subjects within 24 hr; 75 mg was effective only in some subjects. Aloxiprin gave less marked response and a dose of 300 mg was required to inhibit the effect in all volunteers. Where occurring, inhibition of release reaction persisted for three days after treatment with all preparations and restoration to normal occurred in most subjects by the sixth day.

A daily dose of 50 mg claradin for 12-15 days in five volunteers produced complete inhibition of release reaction for most of the treatment period. Inhibition of release reaction took up to 3 days to occur. Normal aggregation returned within 3 days of discontinuing treatment in all subjects. A daily dose of 25 mg claradin gave inconsistent results.

It is suggested that if a trial of acetylsalicylic acid be undertaken for the prevention of arterial thrombosis based on its ability to inhibit platelet release reaction then a daily dose of 50 mg would be sufficient.

Neisseria catarrhalis septicaemia in acute lymphoblastic leukaemia

A case of septicaemia due to Neisseria catarrhalis occurring in an immunosuppressed individual is described. The clinical syndrome closely resembled that of N. meningitidis septicaemia. The potential pathogenicity in the immunosuppressed patient, of organisms usually considered harmless is stressed.

A further application of the nitroblue tetrazolium test

The nitroblue tetrazolium (N.B.T.) test was performed on patients in whom a differential diagnosis of pulmonary thromboembolism or lobar pneumonia existed. The mean N.B.T. score in healthy subjects was 6.4% (range 1%-15%). Patients with uncomplicated pulmonary thromboembolism showed a mean N.B.T. value of 7.5% (range 3%-12%). In patients with lobar pneumonia the mean N.B.T. score was 42.4% (range 21%-85%). These results suggest that the N.B.T. test is of value in the differential diagnosis of pulmonary thromboembolism and lobar pneumonia.

Routine application of the nitroblue tetrazolium test in the clinical laboratory

A modified nitroblue tetrazolium test (NBT) is described which is suitable for routine application in the haematology or bacteriology laboratory and which provides a rapid aid to the diagnosis of bacterial infection. Hitherto published methods have recommended the use of heparinized whole blood samples for the performance of the NBT test. However, we have demonstrated that the use of the sucrose polymer Ficoll permits the test to be carried out on buffy coats prepared from venous blood anticoagulated in sequestrene (EDTA). The mean percentage of NBT-positive neutrophils in 60 healthy control subjects was 6.1. The mean percentage of NBT-positive neutrophils in 56 patients with confirmed or presumed bacterial infection was 34.2. Scores within the normal range were observed in 13 patients in this group. Forty-eight individuals with viral infection yielded a mean percentage of NBT-positive neutrophils of 8.5. Six patients in this group gave scores above the upper limit of normal. Both pathological groups are described in detail and applications of this test are suggested.

Evaluation of an automatic platelet counting system utilizing whole blood

Technicon's newly developed platelet AutoCounter utilizes an electro-optical system which detects and counts particles by sensing the scattering of light which occurs when blood cells flow through the illuminated sensing chamber of a micro-optical system. The system utilizes whole blood collected into EDTA. Blood samples, which can be handled at the rate of 40 per hour, are diluted with 2M urea which in addition causes lysis of the erythrocytes. The haemolysate thus obtained is delivered to the particle counter after a two-minute reaction time, the cell count finally being displayed on a continuous chart recorder. An evaluation of this machine has been carried out in the Department of Haematology, the Royal Infirmary, Edinburgh, on hospital specimens from patients suffering from a wide variety of diseases. The results of this evaluation are presented. Reproducibility studies indicate a coefficient of variation of 4% at any platelet level. The percentage drift per sample ranges from +0.4 to -0.4% of the total count. Carry-over and departures from linearity are statistically significant; however, the magnitude of these deviations is not sufficient to cause concern in routine use. Acceptable agreement is noted between machine counts and the counts obtained by technicians using phase-contrast microscopy with the exception of two anomalous individuals. Discrepant counts were noted in patients with elevation of the erythrocyte sedimentation rate and also in patients with disturbance of immunoglobulins. A modification to the sampling probe which eliminates the former problem is described. The AutoCounter described in this paper provides a fast, reliable, and accurate service laboratory platelet counting system.

Case of tuberous sclerosis and haemorrhagic retinopathy (with fundus photographs)

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