WHITE BLOOD CELLS AND THE DIFFERENTIAL COUNT

RAMLA A. SANDAG – JAILANI , M.D.DEPARTMENT OF PHYSIOLOGY

KKUH / KSU

White Blood Cells (WBC) or Leucocytes

– are the mobile units of the body’s immune defense system. – formed partially in the bone marrow and partially in the lymph tissue.

Leukocytes divide in two categories:

A. Polymorphonuclear Granulocytes - neutrophils - eosinophils - basophils

B. Mononuclear Agranulocytes or Lymphoid cells - lymphocytes - monocytes

* Specific Functions:

Granulocytes } … protect the body against invading organisms mainly by Monocytes } ingesting them ( Phagocytosis )  Lymphocytes } … function mainly in connection with the immune system  

Normal WBC count: (both male and female) = 4 – 11 x 10³/mm³

*Leukocytosis - > 10,000/mm³

*Leukopenia - < 4,000/mm³

– are very active in phagocyting bacteria – most numerous of the WBCs (50 – 70 % of the total leukocytes) – primary defense against infection. – are present in large amount in the pus of wounds. Bands / Stabs – immature forms of neutrophils seen as an early response to infection.

NEUTROPHILS ( Polys, Segs, PMNs)

Neutrophils (cont.)…

Neutrophilia - increase in the number of neutrophils - causes: > acute infection - appendicitis, smallpox or rheumatic fever. > acute inflammation - after a heart attack, burns

Neutropenia - decrease in the number of neutrophils - cause: > viral infection - influenza, hepatitis, rubella.

Neutrophils (cont.)…

A neutrophil has very tiny light staining granules (the granules are very difficult to see). The nucleus is frequently multi-lobed with lobes connected by thin strands of nuclear material.These cells are capable of phagocytizing foreign cells, toxins, and viruses.

– attack parasites and phagocyte antigen-antibody complexes.– account for less than 5% of the WBC’s.– modulate allergic inflammatory responses.

Eosinophilia – increase amount of eosinophils – may be due to parasitic diseases, bronchial asthma or hay fever.

Eosinopenia – decrease amount of eosinophils – may occur when the body is severely stressed.

EOSINOPHIL S

Eosinophils (cont.)…

This granulocyte has large granules (A) which are acidophilic and appear pink (or red) in a stained preparation. The nucleus often has two lobes connected by a band of nuclear material. The granules contain digestive enzymes that are particularly effective against parasitic worms in their larval form.

BASOPHIL S

– secrete anti-coagulant and vasodilatory substances as histamines and serotonin. – represent less than 0–1% of all leukocytes– main function: > secreting substances which mediate the hypersensitivity reaction.

Basophils (cont.)…

Basophilia - an abnormally high number of basophils. > may be associated with: - hemolytic anemia or chicken pox - radiation exposure

Basopenia (Basocytopenia) – decrease number of basophils. > causes: - urticaria - stress - prolonged steroid therapy

Basophils (cont.)…

The basophilic granules in this cell are large, stain deep blue to purple, and are often so numerous they mask the nucleus. These granules contain histamines (cause vasodilation) and heparin (anticoagulant).> The nucleus is either bi-lobed or tri-lobed.

LYMPHOCYTES

– are the second most numerous leukocyte. – account for 20 – 40% of the white blood cells. – not only fight infections but also provide immunity to certain disease. – play an important role in our immune response. *T-lymphocytes act against virus infected cells and tumor cells. *B-lymphocytes produce antibodies.

Lymphocytes (cont.)…

Lymphocytosis – increase in the number of lymphocytes. – Causes: > Infectious mononucleosis or a chronic infection. > Ulcerative colitis > Measles, Mumps, CMV

Lymphocytopenia – decrease number of lymphocytes. – causes: > Chemotherapy, radiation, aplastic anemia > CHF, SLE, renal failure

Lymphocytes (cont.)…

The lymphocyte is an agranular cell with very clear cytoplasm which stains pale blue.Its nucleus is very large for the size of the cell and stains dark purple. This cell is much smaller than the three granulocytes (which are all about the same size).

MONOCYTES

– the largest of the leukocytes. – account for 2 – 6% of all leukocytes. –These cells leave the blood stream (diapedesis) to become macrophages. – As a monocyte or macrophage, these cells are phagocytic and defend the body against viruses and bacteria.

Monocytes (cont.)…

Monocytosis – increase monocyte count – causes: > Bacterial infections > Lymphoma > Subacute Baxcterial Endocarditis (SBE) > TB, Malaria, Typhoid fever

Monocytopenia – decrease monocyte count – causes: > HIV > Steroid treatment

The nucleus is most often "U" or kidney bean shaped; the cytoplasm is abundant and light blue (more blue than this micrograph illustrates).

*What is the WBC/ Leukocyte Differential Count? > Determines the number of each type of white blood cell present in the blood. > Can tell you what type of infection is present.

N⁰ values: Neutrophils = 50 – 70% Eosinophils = 1 – 4% Basophils = 0 – 1% Lymphocytes = 20 – 40% Monocytes = 2 – 6%

ERYTHROCYTE SEDIMENTATION RATE (ESR)

* What is Erythrocyte Sedimentation Rate?

> It is the rate at which erythrocytes settle in a citrated sample of blood in a specific time period, usually one (1) hour.

> Is a nonspecific test used to help detect conditions associated with acute and chronic inflammation.

Sedimentation occurs when the erythrocytes clump or aggregate together in a column-like manner , like “pile of coins”. →ROULEAUX FORMATION

* 2 Commonly used methods of ESR determination:

1. Wintrobe method 2. Westergren method – mostly used

* Reagents and Apparatus:

1. Westergren’s sedimentation apparatus 2. Anticoagulant (EDTA) 3. Disposable sterile syringes and needles

Procedure:

> To perform the test, anticoagulated blood is placed in an upright tube, known as a Westergren tube, and the rate at which the red blood cells fall is measured and reported in mm/h.

Normal results:

After 1 hour: males = 3 – 5 mm females = slightly higher

After 2 hours: males = 7 – 15 mm females = slightly higher

*Increase ESR is seen in:

> Rheumatoid Arthritis (RA), gouty arthritis

> Polymyalgia rheumatica> Temporal arteritis> Pregnancy(3rd month to 3 weeks’ postpartum)> Drugs - Dextran

- Methyldopa - Oral contraceptives - Theophylline - Vitamin A

*Decrease ESR is associated with:

> Polycythemia> Sickle cell anemia> Hereditary spherocytosis> Drugs

- Aspirin - Cortisone - Quinine

* Clinical uses:

1. It is helpful in diagnosing two specific inflammatory diseases, temporal arteritis and polymyalgia rheumatica. 2. It is used to monitor disease activity and response to therapy in both of these diseases. 3. It is a prognostic test.

* A rising ESR can mean an increase in inflammation or a poor response to a therapy; a decreasing ESR can mean a good response.

THANK YOU !