white blood cells · properties of white blood cells neutrophils can attack and destroy bacteria in...
TRANSCRIPT
White Blood Cells
By:
Dr Asma Jabeen
▪ Also called leukocytes
▪ Mobile units of body’s protective
system
▪ Most of them are specifically
transported to areas of serious infection
and inflammation thereby providing a
rapid and potent defense against
infectious agent
White Blood Cells
Leukocytes
Granulocytes Agranulocytes
Polymorphonuclear• Neutrophil• Eosinophil• Basophil
• Lymphocytes
• Monocytes
White blood cells
Granulocytes Non-GranulocytesNeutrophils MonocytesEosinophils LymphocytesBasophils
Polymorphonuclear MononuclearNeutrophils MonocytesEosinophils LymphocytesBasophils
Phagocytes Non-phagocytesNeutrophilsMonocytes LymphocytesMacrophagesEosinophils Basophils
Neutrophils 62%
Lymphocytes 30%
Monocytes 5.3%
Eosinophils 2.3%
Basophils 0.4%
Never Let Monkeys Eat Bananas
Genesis of WBCs
Genesis of white blood cells. The different cells of the myelocyte series are 1, myeloblast; 2, promyelocyte; 3, megakaryocyte;4, neutrophil myelocyte; 5, young neutrophil metamyelocyte; 6, “band” neutrophil metamyelocyte; 7, polymorphonuclear neutrophil; 8,eosinophil myelocyte; 9, eosinophil metamyelocyte; 10, polymorphonuclear eosinophil; 11, basophil myelocyte; 12, polymorphonuclear basophil;13-16, stages of monocyte formation.
Myeloblast
Promyelocyte
Neutrophil myelocyte
Young neutrophil metamyelocyte
Band neutrophilmetamyelocyte
Polymorphonuclearneutrophil
▪ Granulocytes ,monocytes are formed
only in bone marrow▪ Lymphocytes, plasma cells are formed
in spleen, lymph nodes, thymus etc▪ WBCs stored in the bone marrow until
needed in the circulatory system(3 times the quantity as circulate in entire blood)
Life Span of WBCs
➢ 4 to 8 hrs circulating in the blood and 4 to 5 days in tissues where they areneeded.
➢ Serious infection shortens life span
➢ Monocytes 10 to 20 hrs in blood, after that wander to tissues, can live for months as tissue macrophages
Properties of white blood cells
▪ Neutrophils can attack and destroy
bacteria in circulating blood
▪ Tissue macrophages begin life as monocytes (little ability to fight infections) but in tissues are extremely capable of combating intra tissue diseaseagents
Margination
White blood cells
align themselves
along the vessel wall
before leaving the
vessel.
• Neutrophil attracted by glycoproteins(selectins) on endothelial cells
• Adhesion
• Emigration that is
purposeful, directed
and ameboid
Diapedesis
▪ Neutrophils &
monocytes can
squeeze through
pores of blood
capillaries
Ameboid motion
▪ Neutrophils and macrophages can
move through tissues by ameboid
motion
▪ Some cells move through tissue spaces
at velocities 40µm/min
Chemotaxis
Chemical substances in the tissues cause
neutrophils and macrophages to move
towards the source of the chemical.
▪ Depends on concentration gradient of
chemotactic substance
▪ Effective upto 100 µm away from
inflamed tissue
Chemotactic substances
• Bacterial or viral toxins
• Degenerative products of the inflamed tissues themselves, leukotriens and chemicalsreleased from lymphocytes, basophils and mast cells
• Several reaction products of complement themselves(C5a)
• Several reaction products caused by plasma clotting in inflamed area (activated factor XII)
Phagocytosis
➢ Cellular ingestion of the offending agent.
➢ Most important function of the neutrophils and macrophages
Why phagocytosis is selective?
▪ Smooth surfaces of natural tissues
resist phagocytosis
▪ Protective protein coats of natural substances repel the phagocytes
▪ Antibodies (IgG) adhered to bacteria makethem susceptible for phagocytosis
▪ Presence of Complement (C3b) moleculeson bacteria
The selection and phagocytosis process
is called OPSONIZATION.
Phagocytosis by neutrophil
• Neutrophil attaches to cell and projects
pseudopodia• Fusion of pseudopodia and formation of
enclosed vesicle• Free floating phagocytic vesicle • A single neutrophil phagocytize 3 to 20
bacteria
Phagocytosis by macrophage
• Much more powerful than neutrophil
• Capable for phagocytizing 100 bacteria• Engulf larger particles like RBC, malarial
parasites• Extrude the residual products and
survive for many more months
• Lysosomes filled with proteolytic enzymesfuse with phagosome to make it a digestivevesicle.
• Lipases in macrophages
Bactericidal agents help in killing bacteria Oxidizing agents by peroxisomes
▪ Superoxide
▪ Hydroxyl ions▪ Hydrogen peroxide▪ myeloperoxidase
Thank you