24 - Leukocytes. Count and functions of the different leukocyte types. Control of leukopoiesis and leukocyte count in the bloodstream. Immunity.

sections

leukocytes (WBC) count

function of diff leukocytes

leucopoiesis

leukocyte (WBC) count

• white blood cells = 3.5 -10.5*10⁹/L

• Neutrophils = 2.2 - 6.5 X 10⁹/ L - contributes 60-70% of WBC in body

• Eosinophils = contribute to 2-4% of WBC in body

• Basophils = 0.02 - 0.5 X 10⁹/L - contribute 0.5% WBC in body

• Monocytes = 0.1 - 1.0 X 10⁹/ L - contribute 2-5% of WBC in body

• Lymphocytes = 1.3 - 3.9 X10⁹/L - contribute 25-30% of WBC in body

diff leukocytes

• neutrophils

• eosinophils

• basophils

• monocytes

• lymphocytes

neutrophils

• are the first responders to microbial infections

• perform phagocytosis of the bacteria

• Their activity and death in large numbers form pus.

• They are the most common cells seen in acute inflammation

eosinophils

• involved in the detoxification of substances and parasites which are too large to the phagocytosed.

• eosinophils secrete chemicals to destroy parasites

• predominant inflammatory cells in allergic and collagen and spleen diseases, diseases of the CNS.

basophils

• allergic and antigen responses by secretes histamine or anti- inflammatory chemicals.

• Histamine causes vasodialation which helps to increase blood flow to site of injury. Makes blood vessels more permeable so that neutrophils and clotting protein can get to the tissues more easily.

• secrete heparin which is an anticoagulant

Monocyte

• major role in immunity

• involved in the antigen presentation of pathogens to T cells.

• This initiates the desctruction of such pathogens. Monocytes can differentiate to form macrophages

• macrophages perform phagocytosis of pathogens

• Monocytes are also involved in cytokine production.

Lymphocytes

• Natural killer cells are involved in innate immunity

• Defend body from virally infected cells

• T and B cells recognise non- self antigens via antigen presentation.

• They respond in order to eliminate the pathogens or infected cells.

• B lymphocytes produce large quantities of antibodies

• T helper cells produce antibodies that tell the immune response which cytoxic T cells produce granules containing toxic enzymes that kill pathogen infected cells. Once they have carried out function memory cells are created

function of the diff leukocytes

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2. Neutrophils -most abundant white blood cell, contributing to 60-70 % of all white blood cells in the body. Reference range in blood is 2.2- 6.5 X 10^9/ L

   • are the first responders to microbial infections

   • perform phagocytosis of the bacteria

   • Their activity and death in large numbers to the formation of pus. They are the most common cells seen in acute inflammation

3. Eosinophil- contribute towards 2-4% of total white blood cell count.

   • involved in the detoxification of substances and parasites which are too large to the phagocytosed.

   • eosinophils secrete chemicals to destroy parasites

   • predominant inflammatory cells in allergic and collagen and spleen diseases, diseases of the CNS.

4. Basophils- contribute towards less than 0.5% WBC and have a ref value of 0.02- 0.5 X 10^9/L.

   • allergic and antigen responses by secretes histamine or anti- inflammatory chemicals.

   • Histamine causes vasodialation which helps to increase blood flow to site of injury. Makes blood vessels more permeable so that neutrophils and clotting protein can get to the tissues more easily.

   • secrete heparin which is an anticoagulant

5. monocytes: contribute to 2-5% of all leucocytes. Their ref values is 0.1- 1.0 X 10^9/ L.

   • major role in immunity

   • involved in the antigen presentation of pathogens to T cells.

   • This initiates the desctruction of such pathogens. Monocytes can differentiate to form macrophages .

   • macrophages perform phagocytosis of pathogens.

   • Monocytes are also involved in cytokine production.

6. Lymphocytes- contribute to 25- 30% of all leucocytes , ref value 1.3-3.9 X10^9/L

   • Natural killer cells are involved in innate immunity

   • Defend body from virally infected cells

   • T and B cells recognise non- self antigens via antigen presentation.

   • They respond in order to eliminate the pathogens or infected cells.

   • B lymphocytes produce large quantities of antibodies

   • T helper cells produce antibodies that detect the immune response which cytoxic T cells produce granules containing toxic enzymes that kill pathogen infected cells. Once they have carried out function memory cells are created

leucopoiesis

• Creation of white blood cells are formed in the bone marrow of adults and in hemopotoeitc organs in the fetus.

• differentiation of hematopoietic stem cells.

• CSF, - colony stimulating factor involved, IL-3

• These immediate cells lines are mediators of erthrocytes, thrombocytes and also the two forms of white blood cells- myelocytes and lymphocytes