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Risk Stratification in Chronic Lymphocytic Leukemia

The Role of the Clinical Laboratory



ZAP-70 by Flow in CLL

Slide 16

November 2008

This slide demonstrates an example case of ZAP-70 expression detection by flow in a patient with CLL. The top histograms are from the control. The upper left hand histogram quad stats are set such that the upper right hand quadrant contains approximately 0.10% ZAP-70+ B-cells.

 In the upper right hand histogram, we see by using this gating technique in the control specimen that the majority of T-cells and all the NK cells are indeed positive as they should be for ZAP-70. This will serve as an internal positive control.

Once that is established, we can then look at the patient’s results in the bottom histograms by using the same quad stat settings as were established in the control. You can see that 9.2% of the total lymphocyte population is positive for both ZAP-70 and CD19 and 80.1% are ZAP-70 negative.

If one looks in the lower right hand histogram from this particular patient, one sees that the majority of T-cells and all the NK cells are appropriately ZAP-70+, which serves as an internal positive patient control.

To then calculate the percent positivity, the percent ZAP-70+, or 9.2%, is divided into the total B-cell percentage, or 9.2% + 80.1%, which would then equal 10% in this case. This would be interpreted as negative for this patient, remembering that 20% is used as the cut-off point for ZAP-70 positivity.

ZAP-70 by Flow in CLL

 


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