A human circulatory system comprises of Red blood cells, white blood cells and platelets.
You must already be aware of the defence cells of the human body comprising of leukocytes (innate) and antigens, B cells, T cells (adaptive).
Leukocytes are further classified as granulocytes and agranulocytes.
The granulocytes include neutrophils, eosinophils, and basophils.
The agranulocyte consist of lymphocyte and monocytes. White blood cells or WBC plays an extremely significant role in fighting pathogens. Most WBCs are produced by stem cells in bone marrow. The T and B lymphocytes are produced by thymus and spleen respectively. Today we will try to explain each in detail…
Types of Immunity
Innate immune system comes to play instantaneously after an antigen enters the human body. This defence system includes skin, effector cells, antimicrobial peptides, soluble mediators, and cell receptors.
The adaptive immune system is composed of specialized, systemic cells that come to play later in the infection-fighting process and abolish pathogens by inhibiting their growth.
- Granulocytes– as per their name they poses small granules of protein in their cytoplasm
- Neutrophils are most abundantly found phagocytes, forming 60% to 65% of the total flowing white blood cells. They directly attack pathogens and ingest them.
- Eosinophils– Eosinophils play a vital part in the killing of parasites. They have receptors that bind to IgE and has role as professional antigen-presenting cells. They also assist other cells while fighting infections
- Basophils– Least abundantly found granulocytes, less than 2%. Basophils possess receptors that can bind to IgE, IgG and histamine. In case of infection, basophils comes to play and contribute to inflammatory reaction. Mast cells play an immense role in allergic reactions.
- Agranulocytes– Fighter cells with No granules in their cytoplasm
- Lymphocytes– Main fighters of the immune system
- T cells– formed in bone marrow and thymus. Their main role is in the identification of pathogens and remove them
- B Cells- Formed in bone marrow and spleen. Their main role is in the production of antibodies against infection invasion.
- Natural killers– Their main role is in protecting against viruses and cancers by directly attacking them.
- Monocytes– Single nucleus fighter cells whose prime role is in protecting against chronic infections.
The WBCs is measured as blood test parameter total leukocyte count
|Various Age groups||Total leukocyte count per cubic millimeter|
More than normal TLC counts known as leukocytosis means
- Any Infection like bacterial, viral and the like
- After an allergic reaction like status asthmaticus
- After a burn
- Heart attack
- Any injury/ RTA
- Chronic conditions like rheumatoid arthritis, inflammatory bowel disease, or vasculitis
- Leukemia or blood cancer
- After a surgery
- Primary myelofibrosis
Less than normal TLC count or leukopenia means
- Autoimmune disorders like SLE, Evans syndrome
- After chemotherapy, radiation therapy
- After contact with toxins
- Infection in blood
- Vitamin deficiency
- Aplastic anemia
As much as the measurement and effective working of WBCs important to proper functioning of the body, total leukocyte count as a parameter may mean a lot of things. Thus, this vital parameter is seen in conjugation with various other diagnostic parameters to establish a final conclusion.
Dr. Praveen Roy, Clinical Lead & Senior Consultant – Internal Medicine, Dharamshila Narayana Superspeciality Hospital, Delhi