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Communications to the Editor |

Coulter Counter Registers Talc Particles as Leukocytes FREE TO VIEW

Y. C. Gary Lee, MBChB; Kirk B. Lane, PhD; Richard W. Light, MD, FCCP
Author and Funding Information

Saint Thomas Hospital and Vanderbilt University Nashville, TN

Correspondence to: Richard W. Light, MD, Pulmonary Medicine, Saint Thomas Hospital, 4220 Harding Rd, Nashville, TN 37202; e-mail: rlight98@yahoo.com



Chest. 2001;119(2):669-670. doi:10.1378/chest.119.2.669
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Published online

To the Editor:

Use of the Coulter Counter Analyzers for Particle Characterization is an accepted reference method for particle size analysis and is widely used in experimental settings for the measurement of total cell counts in different body fluids.13 We recently found that in pleural fluids induced by the intrapleural injection of talc, the total leukocyte count was higher than expected. We hypothesized that residual talc particles were being counted as leukocytes by the Coulter counter.

To confirm this hypothesis, we analyzed talc solutions of various concentrations using a Coulter Z1 Particle Analyzer (Coulter Electronics; Luton, England). Talc powder (Sigma; St. Louis, MO) was diluted with 0.9% sodium chloride solution into a slurry. The samples were treated with a diluent (Isoton II; Coulter Corporation; Miami, FL) and a lytic reagent to lyse erythrocytes (Zapoglobin II; Coulter Corporation) before analysis. Standard Coulter counter settings for detection of leukocytes were used, under that particles with a diameter between 3.6 μm and 7.47 μm (approximately 25 to 218 fL in volume) were counted. The first reading was discarded, and the mean of the next three readings was recorded. The results are shown in Table 1 .

Talc is a heterogeneous compound with the approximate chemical formula of Mg3(Si2O5)2(OH)2.4 The size of talc particles varies significantly among commercial preparations.5 The median diameter of the commercial talc powder we used was 7.8 μm,5 suggesting that approximately half of the talc particles would fall within the detection range of the Coulter counter. Our results confirmed that the presence of talc particles interferes with the measurement of total leukocyte counts with the Coulter counter.

The Coulter method of counting particles is based on measurable changes in electrical resistance produced by nonconductive particles suspended in an electrolyte. As particles pass through the aperture between electrodes, they displace their own volume of electrolyte. Volume displaced is measured as a voltage pulse; the height of that is proportional to the volume of the particle. This method is independent of particle shape, color, and density. Hence, talc particles of similar volume as leukocytes will be counted as leukocytes. Likewise, various microorganisms in blood or cerebrospinal fluids have been misidentified as leukocytes by the Coulter method.67

Once injected intrapleurally, some of the talc particles will remain in the pleural space for a variable length of time. These residual particles will frequently be mixed with the induced pleural fluid. Investigators should beware that in experimental settings involving the use of talc, total cell counts in body fluids measured with Coulter counter may be falsely elevated. Other methods, eg, a hemacytometer, should be used.

Table Graphic Jump Location
Table 1. Coulter Counter Readings for Solutions of Talc Slurry at Different Concentrations

References

Heaney, LG, McKirgan, J, Standford, CF, et al (1994) Electronic cell counting to measure total cell numbers in bronchoalveolar lavage fluid.Eur Respir J7,1527-1531. [CrossRef] [PubMed]
 
Salinas, M, Rosas, J, Iborra, J, et al Comparison of manual and automated cell counts in EDTA preserved synovial fluids: storage has little influence on the resultsAnn Rheum Dis1997;56,622-626. [CrossRef] [PubMed]
 
Honma, S, Abe, K, Ito, T Pleural free cells in the mouse: quantitative and qualitative cell morphologyArch Histol Jpn1982;45,483-494. [CrossRef] [PubMed]
 
Zazenski, R, Ashton, WH, Briggs, D, et al Talc: occurrence, characterization, and consumer applicationsRegul Toxicol Pharmacol1995;21,218-229. [CrossRef] [PubMed]
 
Ferrer, J, Villarino, MA, Tura, JM, et al Comparison of size and composition of nine different talcs: its relevance for pleurodesis [abstract]. Am J Respir Crit Care Med. 1998;;157 ,.:A66
 
Marshall, BA, Theil, KS, Brandt, JT Abnormalities of leukocyte histograms resulting from microorganisms.Am J Clin Pathol1990;93,526-532. [PubMed]
 
Berger, SA, Waitman, DA, Baruch, R Coulter counter identifiesCryptococcus neoformansas leukocytes: a case of pseudopleocytosisAm J Clin Pathol1992;97,663-664. [PubMed]
 

Figures

Tables

Table Graphic Jump Location
Table 1. Coulter Counter Readings for Solutions of Talc Slurry at Different Concentrations

References

Heaney, LG, McKirgan, J, Standford, CF, et al (1994) Electronic cell counting to measure total cell numbers in bronchoalveolar lavage fluid.Eur Respir J7,1527-1531. [CrossRef] [PubMed]
 
Salinas, M, Rosas, J, Iborra, J, et al Comparison of manual and automated cell counts in EDTA preserved synovial fluids: storage has little influence on the resultsAnn Rheum Dis1997;56,622-626. [CrossRef] [PubMed]
 
Honma, S, Abe, K, Ito, T Pleural free cells in the mouse: quantitative and qualitative cell morphologyArch Histol Jpn1982;45,483-494. [CrossRef] [PubMed]
 
Zazenski, R, Ashton, WH, Briggs, D, et al Talc: occurrence, characterization, and consumer applicationsRegul Toxicol Pharmacol1995;21,218-229. [CrossRef] [PubMed]
 
Ferrer, J, Villarino, MA, Tura, JM, et al Comparison of size and composition of nine different talcs: its relevance for pleurodesis [abstract]. Am J Respir Crit Care Med. 1998;;157 ,.:A66
 
Marshall, BA, Theil, KS, Brandt, JT Abnormalities of leukocyte histograms resulting from microorganisms.Am J Clin Pathol1990;93,526-532. [PubMed]
 
Berger, SA, Waitman, DA, Baruch, R Coulter counter identifiesCryptococcus neoformansas leukocytes: a case of pseudopleocytosisAm J Clin Pathol1992;97,663-664. [PubMed]
 
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