Use of EDTA blood samples for mannosidosis testing

Area of Science:

• Biochemistry
• Clinical Chemistry
• Enzymology

Background:

• Ethylenediaminetetraacetic acid (EDTA) is commonly used as an anticoagulant in blood collection.
• EDTA chelates divalent cations, including zinc (Zn++), which is a crucial cofactor for acidic alpha mannosidase.
• This chelation leads to the inhibition of acidic alpha mannosidase activity in plasma samples.

Purpose of the Study:

• To investigate a method for restoring inhibited acidic alpha mannosidase activity in EDTA-treated plasma.
• To enable reliable estimation of acidic alpha mannosidase activity in EDTA plasma for diagnostic purposes.

Main Methods:

• Preincubation of EDTA plasma samples with a specific concentration (4mM) of zinc chloride (ZnCl2).
• Assay of acidic alpha mannosidase activity following ZnCl2 treatment.
• Correlation of restored enzyme activity with subsequent granulocyte testing for samples exhibiting low activities.

Main Results:

• Addition of 4mM ZnCl2 effectively restored the inhibited acidic alpha mannosidase activity in EDTA plasma.
• The restoration of enzyme activity allowed for accurate quantification in samples previously showing inhibition.
• This method facilitates the use of EDTA plasma for diagnostic assessments involving acidic alpha mannosidase.

Conclusions:

• Preincubation with ZnCl2 is a viable method to overcome EDTA-induced inhibition of acidic alpha mannosidase.
• This technique enhances the utility of EDTA plasma samples for clinical enzyme assays.
• Accurate measurement of acidic alpha mannosidase activity in EDTA plasma can support diagnostic evaluations, particularly when followed by granulocyte tests.