TOTAL EOSINOPHIL COUNT (TEC)

TOTAL EOSINOPHIL COUNT (TEC)

TOTAL EOSINOPHIL COUNT (TEC)

Principle -Whole blood is diluted appropriately using a diluent which lyses the red cells and stains granules in the cosinophils, but does not stain the other leucocytes. The total number of eosinophils in a known volume of known dilution are counted using a counting chamber.

 Diluting fluid-

 1% Aqueous eosin Y 5 ml

 Acetone       5 ml

 Distilled water 90 ml

Specimen- Whole blood, anticoagulated with EDTA. Capillary blood can be used if it is diluted immediately after collection. 

Technique- Prepare 1:20 dilution of the blood in the diluting fluid in the Thoma pipette. Alternatively, add 0.02 ml of blood to 0.38 ml of the diluting fluid. Charge the improved Neubauer counting chamber with the well mixed diluted blood. 

If Thoma pipette is used, discard first few drops before charging the chamber.Allow the cells to settle in a moist chamber for 3 to 5 minutes.Locate the ruled area of the counting chamber under 10 x objective.

Identify the eosinophils by their bright red stained granules. Count the number of eosinophils in the four large corner squares (4 mm) under 40 x objective.

calculation :- toatal eosin count./cu.mm(or µl)

Normal range:- adult 50-450cu.mm (0.05 to 0.45× 10⁹/L)