Flow Cytometry and Polymerase Chain Reaction-Based Analyses of Minimal Residual Disease in Chronic Lymphocytic Leukemia

Table 1

Overview about the most important differences between different MRD detection methods.

	MRD Flow	ASO RQ-PCR
sensitivity	10^−4	10^−4–10^−5
specificity	depends on	depends on
	(i) measured cell type	(i) annealing temperature
	(ii) B cell background	(ii) length of amplified DNA
	(iii) antibody quality
method	(i) surface antigen detection	(i) detection of amplified DNA with individual primer
	(ii) possible antibody combinations:	(ii) possible targets:
	(1) CD20/CD79b/CD19/CD5	(1) Ig heavy chain
	(2) CD20/CD38/CD19/CD5	(2) Ig kappa
	(3) CD22/CD81/CD19/CD5	(3) Ig lamda
limiting factors	(i) high normal B cell background	(i) somatic hypermutation (rare in CLL)
	(ii) antibody quality	(ii) loss of target gene
advantages	(i) high number of cells can be measured	(i) highest sensitivity of all available methods
	(ii) cost effective	(ii) low interference with normal B cells
	(iii) available in day-to-day business
	(iv) rapid (approx. 1 hour)
disadvantages	(i) knowlegment for reliable results	(i) expensive (sequencing, PCR primers)
	(ii) contamination of the system	(ii) time-consuming
		(iii) not available in every diagnostic laboratory