Manual Differential Counts Research Articles

Comparison of white blood cell differential percentages determined by the in‐house LaserCyte hematology analyzer and a manual method

The LaserCyte hematology analyzer (IDEXX Laboratories, Chalfont St. Peter, Bucks, UK) is the first in-house laser-based single channel flow cytometer designed specifically for veterinary practice. The instrument provides a full hematologic analysis including a 5-part WBC differential (LC-diff%). We are unaware of published studies comparing LC-diff% results to those determined by other methods used in practice. To compare LC-diff% results to those obtained by a manual differential cell count (M-diff%). Eighty-six venous blood samples from 44 dogs and 42 cats were collected into EDTA tubes at the Forest Veterinary Centre (Epping, UK). Samples were analyzed using the LaserCyte within 1 hour of collection. Unstained blood smears were then posted to Langford Veterinary Diagnostics, University of Bristol, and stained with modified Wright's stain. One hundred-cell manual differential counts were performed by 2 technicians and the mean percentage was calculated for each cell type. Data (LC-diff% vs M-diff%) were analyzed using Wilcoxon signed rank tests, Deming regression, and Bland-Altman difference plots. Significant differences between methods were found for neutrophil and monocyte percentages in samples from dogs and cats and for eosinophil percentage in samples from cats. Correlations (r) (canine/feline) were .55/.72 for neutrophils, .76/.69 for lymphocytes, .05/.29 for monocytes and .60/.82 for eosinophils. Agreement between LC-diff% and Mdiff% results was poor in samples from both species. Bland-Altman plots revealed outliers in samples with atypical WBCs (1 cat), leukocytosis (2 dogs, 9 cats), and leukopenia (16 dogs, 11 cats). The LaserCyte generated error flags in 28 of 86 (32.6%) samples, included 7 with leukopenia, 8 with lymphopenia, 7 with leukocytosis, 1 with anemia, and 1 with erythrocytosis. When results from these 28 samples were excluded, correlations from the remaining nonflagged results (canine/feline) were .63/.65 for neutrophils, .67/.65 for lymphocytes, .11/.33 for monocytes, and .63/.82 for eosinophils. Although use of a 100-cell (vs 200-cell) M-diff% may be a limitation of our study, good correlation between WBC differentials obtained using the LaserCyte and the manual method was achieved only for feline eosinophils.

Is the inherent imprecision of manual leukocyte differential counts acceptable for quantitative purposes?

Is the inherent imprecision of manual leukocyte differential counts acceptable for quantitative purposes?

Bone Marrow-derived Cells Require a Functional Glucose 6-Phosphate Transporter for Normal Myeloid Functions

Glycogen storage disease type Ib (GSD-Ib) is caused by a deficiency in the ubiquitously expressed glucose 6-phosphate transporter (Glc-6-PT). Glc-6-PT activity has been shown to be critical in the liver and kidney where a deficiency disrupts glucose homeostasis. GSD-Ib patients also have defects in the neutrophil respiratory burst, chemotaxis, and calcium flux. They also manifest neutropenia, but whether Glc-6-PT deficiency in the bone marrow underlies myeloid dysfunctions in GSD-Ib remains controversial. To address this, we transferred bone marrow from Glc-6-PT-deficient (Glc-6-PT(-/-)) mice to wild-type mice to generate chimeric mice (BM-Glc-6-PT(-/-)). As a control, we also transferred bone marrow between wild-type mice (BM-Glc-6-PT(+/+)). While BM-Glc-6-PT(+/+) mice have normal myeloid functions, BM-Glc-6-PT(-/-) mice manifest myeloid abnormalities characteristic of Glc-6-PT(-/-) mice. Both have impairments in their neutrophil respiratory burst, chemotaxis response, and calcium flux activities and exhibit neutropenia. In the bone marrow of BM-Glc-6-PT(-/-) and Glc-6-PT(-/-) mice, the numbers of myeloid progenitor cells are increased, while in the serum there is an increase in granulocyte colony-stimulating factor and chemokine KC levels. Moreover, in an experimental model of peritoneal inflammation, local production of KC and the related chemokine macrophage inflammatory protein-2 is decreased in both BM-Glc-6-PT(-/-) and Glc-6-PT(-/-) mice along with depressed peritoneal neutrophil accumulation. The neutrophil recruitment defect was less severe in BM-Glc-6-PT(-/-) mice than in Glc-6-PT(-/-) mice. These findings demonstrate that Glc-6-PT expression in bone marrow and neutrophils is required for normal myeloid functions and that non-marrow Glc-6-PT activity also influences some myeloid functions.

Laboratory Productivity and the Rate of Manual Peripheral Blood Smear Review: A College of American Pathologists Q-Probes Study of 95 141 Complete Blood Count Determinations Performed in 263 Institutions

Automated laboratory hematology analyzers are capable of performing differential counts on peripheral blood smears with greater precision and more accurate detection of distributional and morphologic abnormalities than those performed by manual examinations of blood smears. Manual determinations of blood morphology and leukocyte differential counts are time-consuming, expensive, and may not always be necessary. The frequency with which hematology laboratory workers perform manual screens despite the availability of labor-saving features of automated analyzers is unknown. To determine the normative rates with which manual peripheral blood smears were performed in clinical laboratories, to examine laboratory practices associated with higher or lower manual review rates, and to measure the effects of manual smear review on the efficiency of generating complete blood count (CBC) determinations. From each of 3 traditional shifts per day, participants were asked to select serially, 10 automated CBC specimens, and to indicate whether manual scans and/or reviews with complete differential counts were performed on blood smears prepared from those specimens. Sampling continued until a total of 60 peripheral smears were reviewed manually. For each specimen on which a manual review was performed, participants indicated the patient's age, hemoglobin value, white blood cell count, platelet count, and the primary reason why the manual review was performed. Participants also submitted data concerning their institutions' demographic profiles and their laboratories' staffing, work volume, and practices regarding CBC determinations. The rates of manual reviews and estimations of efficiency in performing CBC determinations were obtained from the data. A total of 263 hospitals and independent laboratories, predominantly located in the United States, participating in the College of American Pathologists Q-Probes Program. There were 95,141 CBC determinations examined in this study; participants reviewed 15,423 (16.2%) peripheral blood smears manually. In the median institution (50th percentile), manual reviews of peripheral smears were performed on 26.7% of specimens. Manual differential count review rates were inversely associated with the magnitude of platelet counts that were required by laboratory policy to trigger smear reviews and with the efficiency of generating CBC reports. Lower manual differential count review rates were associated with laboratory policies that allowed manual reviews solely on the basis of abnormal automated red cell parameters and that precluded performing repeat manual reviews within designated time intervals. The manual scan rate elevated with increased number of hospital beds. In more than one third (35.7%) of the peripheral smears reviewed manually, participants claimed to have learned additional information beyond what was available on automated hematology analyzer printouts alone. By adopting certain laboratory practices, it may be possible to reduce the rates of manual reviews of peripheral blood smears and increase the efficiency of generating CBC results.

Performance Evaluation of the Immature Granulocyte Parameter on the Sysmex XE-2100 Automated Hematology Analyzer

Recently, St. Anthony's Medical Center Laboratory (SAMC) in St. Louis, Missouri, installed a new automated hematology analyzer, the Sysmex XE-2100. The XE-2100 has an additional differential parameter, the immature granulocyte (IG) parameter. Prior to implementation, the IG parameter was evaluated by comparison to the manual immature granulocyte count. Immature granulocytes counted manually, as well as the automated count, included metamyelocytes, myelocytes, and promyelocytes. Manual differentials were performed on each specimen by 2 experienced medical technologists using the National Committee for Clinical Laboratory Standards (NCCLS) document H20-A. In addition to evaluating the IG parameter, St. Anthony's laboratory plans to report the automated IG count from the XE-2100, with <or=0.54 IG percentage and <or=0.1 x 103 IG number considered to be normal and to redefine its manual review criteria. An IG percentage >or=5% and an absolute IG number of >or=0.5 x 103 will require differentiation by a manual differential count. An IG percentage <5% and an absolute IG number of <0.5 x 103 will not require differentiation by manual slide review. In this comparison of the IG count on the XE-2100 to the manual count, the correlation coefficient was 0.83. The XE-2100 IG results showed significant correlation with the results from the manual immature granulocyte count. We concluded that the XE-2100 IG demonstrated comparable performance to the manual IG count.

Performance of an Automated Immature Granulocyte Count as a Predictor of Neonatal Sepsis

Neonatologists use immature granulocytes (IG) in manual differential counts as an indicator of sepsis. This study was designed to compare the predictive ability of automated vs manual IG counts for neonatal sepsis. Infants undergoing sepsis evaluation were identified prospectively for study if a CBC count was obtained in temporal proximity to the blood culture. Automated IG counts were obtained from the research software of the Sysmex XE-2100 (Sysmex, Kobe, Japan). Manual average IG counts were obtained from two 100-cell manual differential counts independently performed by a technologist and a hematopathology resident. A comparative analysis of manual and automated IG counts showed considerable overlap of ranges. The highest positive blood culture rate occurred in the nonneutropenic preterm subset of infant older than 7 days (21/55 [38%]). For these infants, elevated IG counts by manual and automated methods were associated significantly with positive blood culture results (odds ratio, manual, 3.74; odds ratio, automated, 3.63), albeit with low sensitivity.

Utility of automated counting to determine absolute neutrophil counts and absolute phagocyte counts for pediatric cancer treatment protocols

Absolute neutrophil counts (ANCs) and absolute phagocyte counts (APCs) are used to guide cancer treatment. Although automated counting could replace manual counting, data showing correlations are lacking. By analyzing blood samples from children undergoing cancer treatment, the authors determined whether ANCs and APCs obtained by automated methods correlated positively with ANCs and APCs obtained manually. The authors analyzed 3640 consecutive peripheral blood samples. Leukocyte counts determined by Beckman-Coulter Gen-S or HmX analyzers (Beckman-Coulter, Miami, FL) were used to calculate counts obtained by automated or manual methods. Automated differential counts were obtained by automated analyzers and manual differential counts were performed by medical technologists. Counts underwent linear regression analysis. The authors evaluated 5 cutoff values for ANCs and APCs commonly used in decision-making related to cancer treatment: 300/muL, 500/muL, 750/muL, 1000/muL, and 1500/muL. Manually determined ANCs and APCs served as standards to determine the sensitivity, specificity, positive and negative predictive values, and kappa coefficient for automated counting. R(2) values were 0.81 for ANCs determined by manual and automated methods and 0.84 for APCs determined by both methods. The specificity of the automated method was > 90% for all ranges of ANCs and APCs, except one (APCs < 300/muL). There was excellent agreement (kappa > 0.9) between ANCs determined by manual and automated methods and APCs calculated by both methods. Automated methods of determining ANCs and APCs for children undergoing cancer treatment were reliable and can replace manual counting. Blood smear examination to validate ANCs and APCs determined by automated methods was needed only in selected cases.

A Comparison of Automated and Manual Leukocyte Differential Counts and The Detection of Lymphoid Blast Cells For Diagnosis and Treatment Decisions in Pediatric Oncology.

A Comparison of Automated and Manual Leukocyte Differential Counts and The Detection of Lymphoid Blast Cells For Diagnosis and Treatment Decisions in Pediatric Oncology.

Flow cytometric evaluation of canine bone marrow based on intracytoplasmic complexity and CD45 expression.

Because of the complexity, subjectivity, time, and technical skill required for determination of manual bone marrow differential cell counts, an alternative method is needed. Several flow cytometric methods have been described, but all have limitations. The purpose of this study was to evaluate a technique for bone marrow differential cell counting based on flow cytometric evaluation of CD45 expression and intracellular complexity (CD45 scatter plots). Bone marrow was obtained from 15 dogs that were being evaluated for hematologic disorders. In preliminary studies, the location of bone marrow subpopulations in the CD45 scatter plots was evaluated by labeling bone marrow with lineage-specific markers. A template was developed to identify these cell populations. Gates were set to identify granulocytes, myeloblasts, monocyte/macrophages, lymphocytes, and nucleated erythroid populations. The CD45 labeling technique accurately quantified granulocytes, myeloblasts, erythroid precursors, and lymphocytes in canine bone marrow. Correlation coefficients with manual counts for granulocytes, myeloblasts, erythroid cells, lymphocytes, and monocyte/macrophages were 0.90, 0.89, 0.96, 0.91, and 0.54, respectively. The capacity of the CD45 scatter-plot technique to quantify lymphocytes and myeloblasts is an advantage over previously described techniques. The simplicity of the CD45 labeling method and the ease with which batches of samples can be analyzed makes the technique potentially applicable as a routine test in clinical and research laboratories.

Do automated hematology counters replace the manual differential count?

Die automatisierte Differenzierung des Blutbildes eignet sich gut als Screening-Untersuchung in Praxis und Spital. Durch Kennen der Stärken und Schwächen des eingesetzten Analysegerätes können entscheidende Informationen aus der automatisierten Untersuchung gewonnen und auf eine unnötige zeitintensive mikroskopische Differenzierung kann verzichtet werden. Finden sich numerische Aberrationen der Erythrozyten, Leukozyten und Thromboyzten oder abnorme Zellpopulationen, ist bei der Erstuntersuchung immer eine mikroskopische Nachkontrolle indiziert. Die mikroskopische Differenzierung ist somit in speziellen Fällen eine wichtige Ergänzung des automatisierten Blutbildes und kann auch durch moderne Analysegeräte nicht ersetzt werden.

Neonatal nucleated red blood cells in G6PD deficiency.

The objective of this study is to study the absolute number of nucleated red blood cells (RBC) at birth, an index of active fetal erythropoiesis, in infants with G6PD deficiency and in controls. We tested the hypothesis that hematocrit and hemoglobin would be lower, and absolute nucleated RBC counts higher, in the G6PD deficient and that these changes would be more prominent in infants exposed passively to fava bean through maternal diet. Thirty-two term infants with G6PD deficiency were compared with 30 term controls. Complete blood counts with manual differential counts were obtained within 12 hours of life. Absolute nucleated RBC and corrected leukocyte counts were computed from the Coulter results and the differential count. G6PD deficient patients did not differ from controls in terms of gestational age, birth weight, or Apgar scores or in any of the hematologic parameters studied, whether or not the mother reported fava beans consumption in the days prior to delivery. Although intrauterine hemolysis is possible in G6PD deficient fetuses exposed passively to fava beans, our study supports that such events must be very rare.

Serial measurements of hematologic counts during the active phase of human granulocytic ehrlichiosis.

To describe the changes that occur in blood count parameters during the natural course of human granulocytic ehrlichiosis, we designed a retrospective cross-sectional case study of 144 patients with human granulocytic ehrlichiosis and matched controls who had a different acute febrile illness. Patients from New York State and the upper Midwest were evaluated from June 1990 through December 1998. Routine complete blood counts and manual differential leukocyte counts of peripheral blood were performed on blood samples that were collected during the active illness, and values were recorded until the day of treatment with an active antibiotic drug. Thrombocytopenia was observed more frequently than was leukopenia, and the risk of having ehrlichiosis varied inversely with the granulocyte count and the platelet count. Patients with ehrlichiosis displayed relative and absolute lymphopenia and had a significant increase in band neutrophil counts during the first week of illness. Knowledge of characteristic complete blood count patterns that occur during active ehrlichiosis may help clinicians to identify patients who should be evaluated specifically for ehrlichiosis and who should receive empiric antibiotic treatment with doxycycline.

Flow cytometric evaluation of canine bone marrow differential cell counts.

Three flow cytometric techniques were evaluated for determination of differential cell counts on canine clinical bone marrow specimens. Techniques included staining bone marrow specimens with 2'7'-dichlorofluorescein (DCF) or 3,3'-dihexyloxacarbocyanine iodide (DiOC6) and evaluation of forward-angle light scatter vs. side-angle light scatter plots. Flow cytometric evaluation of bone marrow cells stained with DCF failed to separate bone marrow cells into distinct cell populations. Staining with DiOC6 resulted in separation of bone marrow cells into populations of mature and immature erythroid cells, mature and immature myeloid cells, and lymphocytes. The scatter plot method resulted in identification of mature and immature erythroid cells, immature myeloid cells, metamyelocytes, and bands and segmenters. Lymphocytes could not be differentiated from mature erythroid cells by the scatter plot method. When the results of the DiOC6 method and the scatter plot method were compared with manual bone marrow differential cell counts, the scatter plot method had more similar mean values and higher correlation coefficients. The scatter plot method has the potential of providing rapid semiquantitative assessment of bone marrow differential cell counts in dogs for specimens that contain low numbers of lymphocytes.

Diagnostic potential of neutrophil elastase inhibitor complex in the routine care of critically ill newborn infants

It has been suggested that determination of the neutrophil elastase alpha1-proteinase inhibitor complex (E-alpha1PI) improves the diagnosis of bacterial infection in newborns. We evaluated the use of E-alpha1PI measurements in 143 newborns, consecutively admitted to a tertiary intensive care unit, employing a new random access assay and a sampling procedure that minimises post-collection artefacts. The 95% range for noninfected newborns was 20-110 microg/l up to the 5th day of life and 20-85 microg/l thereafter. The sensitivity as to the diagnosis of culture-proven bloodstream infection was 80% for E-alpha1PI, 86% for the immature to total neutrophil ratio, 64% for C-reactive protein and 37% for the total white blood cell count. The corresponding specificity amounted to 97%, 85%, 85% and 86%, respectively. E-alpha1PI increases preceded elevations of C-reactive protein by 18 h. Like C-reactive protein, E-alpha1PI levels did not distinguish between bloodstream infection and non-bacterial inflammatory responses. Results of E-alpha1PI became available within 1 h of collection and usually 2-3 h before manual leucocyte counts. Determination of neutrophil elastase alpha1-proteinase inhibitor levels yields diagnostic advantages comparable to those of manual differential counts but provide faster turnaround times.

Value of neutrophil CD16 expression for detection of left shift and acute-phase response.

Fc gamma RIII (CD16) expression of neutrophil granulocytes was measured in 156 patients by means of fluorescence-labeled antibodies with a flow cytometer. Results were compared with (1) 400-cell manual differential count; (2) left shift flagging on hematology analyzers; (3) absolute neutrophil count; and (4) acute-phase protein levels. Asynchrony was noted between neutrophil CD16 expression and microscopically defined neutrophil stage, particularly in heavily left-shifted samples, which made it impossible to reliably enumerate immature neutrophils on the basis of CD16 expression. According to receiver operating characteristics, the absolute count of CD16-negative neutrophils was highly discriminatory for detection of left shift, with an area under the curve (AUC) of 0.842 +/- 0.03 (SE) and maximum efficiency of 81% +/- 3%, but absolute neutrophil count was not significantly inferior (0.821 +/- 0.03 and 76% +/- 3%). STKS and SE9000 flagging demonstrated efficiency of 76% +/- 3% and 81% +/- 3%, respectively. For detection of acute-phase response, absolute neutrophil count (AUC, 0.836 +/- 0.04; maximum efficiency, 80% +/- 4%) outperformed both quantitative neutrophil CD16 expression (0.760 +/- 0.05; 75% +/- 4%) and absolute CD16-negative neutrophil count (0.757 +/- 0.05; 71% +/- 4%); absolute band count performed similarly (0.853 +/- 0.04; 79% +/- 4%) and showed high efficiency at high sensitivity and specificity. Efficiency of analyzer flagging for detection of acute-phase response was not superior to absolute neutrophil count (STKS, 77% +/- 4%; SE9000, 78% +/- 4%). In conclusion, the diagnostic value of measuring neutrophil CD16 expression was generally similar to that of less complicated analytes.

Laboratory tests in evaluation of acute febrile illness in pediatric emergency room patients.

The rising costs of health care and the movement for health care reform have focused attention on methods of cost containment. Of routine laboratory and radiologic procedures, complete blood cell count (CBC) and determination of serum electrolyte values rank as high as 2nd and 9th in overall cost. We retrospectively studied use of the clinical laboratory to aid diagnosis of an acute infectious event in a pediatric emergency department population. For 5 months, we reviewed medical records of pediatric patients younger than 15 years brought to the emergency department because of a febrile episode. Of 155 cases reviewed, electrolyte concentrations were determined in 108 patients and CBC in 155. In all patients, either culture or rapid test for streptococcal organisms was performed. In addition, 838 pediatric patients with similar symptoms but who did not undergo laboratory testing were monitored for 100 days. Measures of effectiveness including sensitivity, specificity, positive and negative predictive values, and likelihood ratio were used to correlate specific laboratory findings with antibiotic therapy, serious bacterial disease, and culture positivity. Electrolyte abnormalities were found largely to be dismissed clinically, with the major clinical response consisting of parental education about hydration. The CBC profile was evaluated, with white blood cell count (WBC) indicator limits of > 10,000, > 10,000 but < 15,000, and > 15,000/mm3, and differentiated into absolute neutrophil count, neutrophil percent, and band cell percent. Temperature was evaluated as an independent variable. Insofar as serious bacterial disease and culture positivity, sensitivity was uniformly low (70%), and specificity was only marginably acceptable for WBC > 15,000 (77%). Both positive predictive values and likelihood ratio were low with respect to predicting either serious bacterial disease or culture positivity, emphasizing the limited usefulness of these clinical laboratory measurements. The best hematologic predictors of serious bacterial disease or culture positivity were obtained with automated hematologic analyzers and exceeded manual differential measurement of neutrophil percent and band cell percent. In addition, we correlated the administration of antibiotics with the various hematologic parameters and discovered that WBC > 15,000, regardless of cause, almost uniformly resulted in treatment (positive predictive value, 93.5%; likelihood ratio, 5.60). These findings support the use of automated hematology analyzer-derived measurements and question the use of manual differential counts, unless specific issues are to be addressed. Furthermore, the findings seem to support more reliance on clinical impression and less on laboratory values.

Evaluating the CELL-DYN 3500 haematology analyser in an acute general hospital.

The CELL-DYN 3500 (CD3500) (Abbott Diagnostics Division, Santa Clara, CA, USA) is a multiparameter, automated haematology analyser system capable of producing 22 haematological parameters including a screening five-part differential. The evaluation was performed in a recently expanded acute care general hospital. Studies of linearity, carryover and precision were acceptable and within manufacturer's stated limits. Correlation of CD3500 with manual differential counts were good except for the basophil count. The white cell flagging system had a sensitivity of 83.6% and specificity of 88.9% with 85.6% agreement. The platelet flagging system also had comparable sensitivity and specificity rate of 88.4% and 94.5% and agreement rate of 92.2%. The overall false positive rate and false negative rate for both the white cell and platelet flags combined were 8.6% and 10.3%. All samples provided a differential with no rejection experienced. The MAPSS technology, together with the extended lyse mode and the investigational nine-part differential provides potential for future development in WBC differential.

Blood transfusion for haemolytic disease as a cause of leukocytosis in the fetus.

We evaluated the effect of fetal intravascular transfusion (IVT) of leukocyte-poor red blood cells to correct fetal anaemia due to haemolytic disease on the fetal leukocyte count in 153 patients. Initial, mid-transfusion, and closing haematological studies were obtained when possible. The effect on leukocyte subsets was evaluated by the manual differential count. Fetal leukocyte count increased an average of 18.0 per cent during all IVTs (P < 0.01), despite the dilutional effect of the transfusion. The degree of leukocytosis increased with subsequent transfusions. The smallest (10.1 per cent) change occurred during the initial transfusion. A 41.8 per cent increase was noted during the sixth procedure. There was no relation between leukocytosis and gestational age, volume of transfusion, changes in umbilical vein pressure, or hydrops. Forty-two per cent of the increase was due to expansion of the neutrophil pool and 22 per cent was due to expansion of the monocyte pool. The neutrophil count increased 29 per cent (P < 0.01) and monocytes increased 64.7 per cent (P < 0.001). There was no change in eosinophil and lymphocyte counts. Both an immune aetiology and an effect of inflammatory agents may contribute to this leukocytosis.

Automated Differential White Blood Cell Counts in the Young Pediatric Population

The significance of the white blood cell differential in young children is not well defined. The relationship of the new automated flow cytometric techniques to the manual differential, moreover, has not been established for this age group. We compared automated white counts with manual differential white counts performed on peripheral blood collected from children younger than 3 years. We compared these results with those obtained on adults. The automated neutrophil and lymphocyte counts showed poorer correlations (r = 0.86 and 0.90, respectively) with manual counts compared with the adult results (r = 0.94 and 0.96). Correlations for eosinophils, monocytes, and basophils also were lower. When flagged and nonflagged samples were analyzed separately, correlations of nonflagged differentials with manual counts were better but remained lower than correlations for adults. Seventy-one percent of the specimens “flagged” abnormalities that required microscopic evaluation, compared with 33% in the adult hospital population.

Differentiation of segmented and band neutrophils during the early newborn period

This prospective study evaluated the degree of inter-reader variability in the identification of segmented and band neutrophils from blood smears of full-term, healthy neonates. Wide inter-reader differences of band neutrophil identification and the immature to total neutrophil ratio were observed. Because of poor correlation between evaluators of the same blood smear, the clinical utility of the manual differential leukocyte count in the evaluation of neonates is limited. (J P EDIATR 1995;127:298-300)