Absolute Eosinophil Count

Absolute Eosinophil CountDr. Mohammed Abdul AleemPractical Pathology Osmania Medical College1

The eosinophil is slightly larger than the neutrophil, with a diameter of 1217 m. The nucleus is usually bilobed but occasional nuclei are trilobed.Eosinophil granules are spherical; they pack the cytoplasm and stain reddishorange. The cytoplasm is weakly basophilic, ribosomes and rough ER are abundant.Principle:A sample of blood is diluted with a solution that selectively stains the eosinophils and eliminates all other leukocytes and erythrocytes from view. Following mixing, the specimen is introduced into the counting chamber and the number of eosinophils in a known volume of blood is counted.Blood Sample:Direct capillary blood or EDTA anti-coagulated blood is used for Absolute Eosinophil Count.

Method:There are two methods:

1. Improved Neubauer chamber method2. Fuchs-Rosenthal counting chamber method

Diluting fluid: For both methods, Dungers diluting fluid is used. Composition:1. Eosin 1% (aq) Solution 5 ml2. Acetone 5 ml.3. Distill water 100 ml.

Eosin stains the eosinophil granules bright red, water is used to lyse red cells and acetone is meant for fixation of eosinophils.ProcedureSuck anticoagulated blood up to mark 1 in WBC pipetteWipe tip and outside of the pipette.Draw diluting fluid up to mark 11 in the WBC pipette to get dilution of 1:10.Mix well by rotating the pipette.Charge the Neubauers chamber after discarding 1-2 drops of the mixture from the WBC pipette.Allow the cells to settle down for a few minutes.Count the eosinophils under low power (10x) in 4 large corner squares.Eosinophils are identified by having brightly red granules.Calculations:

Number of eosinophils in 1 mm3 = (nx10)/4

(Dilution factor = 10)

Hence, Number of eosinophils per mm3 (l)= n 10

Number of eosinophils in 1 mm3 = n 25

(n is the total number of eosinophils counted in 4 corner squares)Fuchs-Rosenthal Chamber:In this chamber, count the cells in entire 16 sq. mm area. The depth of chamber is 0.2 mm.Hence more cells are counted and gives more accurateresult.

Normal Range:

40-400 per microliter.1. Allergic disorders:i. Bronchial asthmaii. Urticariaiii. Hay feveriv. Drug hypersensitivity

2. Parasitic infestationsi. Roundwormii. Hookwormiii. Tapewormiv. Echinococcosis

3. Skin diseasesi. Pemphigusii. Dermatitis herpetiformisiii. Erythema multiforme

4. Pulmonary diseasesi. Lefflers syndromeii. Tropical eosinophilia

5. Haematopoietic diseasesi. Chronic myeloid leukaemiaii. Polycythaemia veraiii. Hodgkins diseaseiv. Pernicious anaemia

6. Miscellaneous conditionsi. Rheumatoid arthritisii. Polyarteritis nodosaiii. Sarcoidosisiv. IrradiationEosinophil leucocytosis EosinophiliaCauses of EosinopeniaAcute stress including trauma, surgery, burns, epileptiform convulsions, acute infections, acute inflmmation, MI, anoxia and exposure to cold Cushing syndromeAdministration of various Drugs including corticosteroids andACTH, epinephrine (adrenaline) and other agonists, histamine and aminophyllineHaemodialysis (during procedure)