Flow cytometry for PNH

Last updated: Friday, 04, June, 2010
See also Flow cytometry.

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Item Process
Specimen5 mL blood in lithium heparin, ACD or EDTA.
Method

The red cells and neutrophils are stained with directly conjugated antibodies specific for two of several GPI-linked proteins eg, CD55, CD58, CD59 and CD66b.

The stained cells are then analysed by flow cytometry.

The percentage of the affected red cells and neutrophils are reported as well as the antigens which are expressed at lower levels.

Application

Investigation of haemolytic anaemia, recurrent haemoglobinuria, hypoplastic anaemia, and other obscure anaemia.

The analysis of neutrophils for GPI-linked proteins is more sensitive as the proportion of abnormal neutrophils is usually higher than the proportion of PNH red cells. This is because of the reduced survival of PNH red cells compared to normal and because of the effect of transfusions.

Interpretation

The absence or reduced expression of the measured GPI-linked proteins can be indicative of PNH.

The presence of a population of cells with a deficiency of two or more GPI-linked proteins is diagnostic of PNH.

Reference

Dacie JV and Lewis SM. Practical Haematology. 8th edn. Churchill Livingstone 1996.

Hillmen P et al. B J H 2000; 108:470-479.