WBC- WHITE BLOOD CELLS COUNT
WBC or leukocytes are the cells of the immune system defending the body against infectious diseases
and foreign material.
All leukocytes derive from a hematopoietic stem cell in the bone marrow and differentiate as needed.
(Maturation and differentiation can take place in other organs).
They live about 3 to 4 days and are found throughout the body blood and lymphatic system
The number of leukocytes in the blood is often an indication of disease:
↑WBC: Leukocytosis
↓WBC: Leukopenia
There are 5 different types of leukocytes:
1. Granulocytes: (granules are membrane bound enzymes involved in the digestin of endothelial
particles)
 Neutrophils
 Eosinophils
 Basophils
2. Agranulocytes:
 Lymphocytes
 Monocytes
I.
NEUTROPHILS:
Combat pyogenic infection (bacteria and fungi) through phagocytosis
The nucleus is irregular. The nucleus of mature cells appear segmented.
They are referred to as polymorphonuclear neutrophils or segs.
They die after ingesting a few pathogen (pus formation)
Sudden demand of neutrophils such as in acute bacterial infection forces the body to create cells
quickly. The nuclei of these immature cells are not segmented. These immature cells are referred to as
bands or stabs, and the term shift to the left is used to describe the distribution of the mature and
immature cells. A shift to the left is indicative of an infection in progress.
Causes of neutrophilia (↑neutrophils)
 Acute bacterial infection (with shift to the left)
 Many inflammatory processes
 Physical stress
 Tissue necrosis (burn victims, myocardial infarction)
 Granulocytic leukemia
Causes of neutropenia (↓neutrophils)
 Viral infections (hepatitis, influenza, rubeola, rubella, mumps)
 Some bacterial infections (typhoid fever)
 Overwhelming infection – can deplete the bone marrow
 Many anti-neoplastic drugs (bone marrow suppression)
 Drugs (Some antibiotics, lithium, psychotic drugs)
II. EOSIOPHILS:
Responsible for the antigen-antibody reaction.
The most common cause of increased Eosinophils is allergy ( Hayfever, asthma, drug hypersensitivity)
Decreased by corticosteroid drugs.
III. BASOPHILS:
Small percentage of the total leukocytes
Phagocytic function. Role in parasitic infections and allergies.
They contain heparin, histamine, and serotonin and create a vasodilation reaction
IV. LYMPHOCYTES:
Primary components of the immune system.
Source of serum immunoglobulin and cellular immune response.
Role in immunological reactions.
All lymphocytes are produced in the bone marrow:
 B-cells are produced and matured in the marrow.
B-cells play a role in the humoral immune response. Make antibodies against the antigens and
develop into memory cells.
 T-cells are produced in the marrow and matured in the thymus gland.
T-cells directly attack the cells infected by the organism
In a CBC the lymphocyte count give the total of B-cells and T-cells. B-cells and T-cells work together to
help provide protection against infection, oncogenic agents, and foreign tissue.
Bothe B-cells and T-cells work together to help provide protection against infection, oncogenic agents,
and foreign tissue
Causes of lymphocytosis (↑lymphocytes)
 Lymphatic leukemia/ lymphoma
 Infectious lymphocytosis in children
 Infectious mononucleosis
 Viral diseases
o Viral upper respiratory tract infection
o Measles, mumps, chicken pox
o Infectious hepatitis (acute viral)
o Toxoplasmosis
 Crohn’s disease, Ulcerative colitis
Causes of lymphopenia (↓lymphocytes)
 Chemotherapy, radiation, immunosuppressive medications
 Cortisone
 Aplastic anemia
 Hodgkins disease
 Inherited or acquired immunodeficiencies (AIDS)
 Severe debilitating illness
V. MONOCYTES:
Agranulocytes
Largest cells in the blood
Second line of defense against infection
They are generated in the bone marrow, circulate in the blood stream and move into tissues throughout
the body where they differentiate into macrophages and dendritic cells.
They remove injured cells, dead cells, microorganisms, and insoluble particles from the blood.
Monocytosis is seen in bacterial infections and some cancers