Table 4.

Precision of Detection of Atypical Plasma Cells by 10-Color Multiparameter Flow Cytometry ^a

	Abnormal PCs		Total PCs		Abnormal PCs			Abnormal PCs		Total PCs		WBCs
Tube No.	No.	Mean (% CV)	No.	Mean (% CV)	% of WBCs	Mean (% CV)		% of Total PCs	Mean (% CV)	% of WBCs	Mean (% CV)	No.	Mean (% CV)
1	4,538		11,811		0.3301			38.4218		0.8592		1,374,666
2	773	740.3 (3.8)	8,406	8,519.3 (1.2)	0.0383	0.0391 (2.1)		9.1958	8.6935 (5.0)	0.4161	0.4507 (6.7)	2,019,964	1,894,977 (5.8)
	725		8,537		0.0399			8.4924		0.4702		1,815,533
	723		8,615		0.0391			8.3923		0.4658		1,849,434
3	123	113.0 (9.9)	9,970	9,735.3 (6.8)	0.0057	0.0067 (13.1)		1.2337	1.1662 (13.5)	0.4646	0.5824 (20.2)	2,146,026	1,717,540.7 (21.7)
	101		10,244		0.0069			0.9859		0.7001		1,463,180
	115		8,992		0.0075			1.2789		0.5826		1,543,416
4	27	30.0 (10.0)	11,970	13,053.7 (10.4)	0.0015	0.0016 (5.5)		0.2256	0.2299 (3.0)	0.6486	0.6797 (4.6)	1,845,478	1,917,478 (6.1)
	30		12,606		0.0016			0.2380		0.6799		1,854,164
	33		14,585		0.0016			0.2263		0.7105		2,052,792
5	0.0		1,010.0		0.0000			0.0000		0.3701		272,866

CV, coefficient of variation; PC, plasma cell.

a A bone marrow aspirate sample containing no plasma cells was spiked with abnormal plasma cells (tube 1) before being serially diluted in triplicate (tubes 2-5) to a target cell number of 30 to 50 plasma cells (tube 4). The average imprecision of the three diluted samples in tube 4 was comparable to the theoretical limit of detection for each sample as determined by Poisson counting statistics.