White cells Flashcards
What are granulocytes?
Refers to neutrophils, basophils or eosinophils
Granules present in the cytoplasm containing agents responsible for the phagocytic function
What are monocytes?
Monocytes are precursors of tissue macrophages
What are granulocytes and monocytes derived from?
Myeloid progenitor stem cells
What do myeloid progenitor stem cells arise?
Erythrocytes
Mast cells
Megakaryocytes
Myeloblasts(Granulocytes+Monocytes)
What growth factors influence the synthesis of white cells?
Granulocyte colony-stimulating factor (G-CSF)
Granulocyte macrophage-colony stimulating factor (GM-CSF)
Where are leukocytes produced?
Produced in bone marrow and the thymus gland(Majority of t cells from thymus before birth)
What are neutrophils?
Non-specific immune system and responsible for digesting and engulfing of pathogens through phagocytosis
What substances are produced by basophils?
Histamines
What role do histamines perform?
Increases permeability of the capillaries to white blood cells, encourages leukocytes to engage with pathogen
Affects blood flow to affected area, increases concentraiton of leukocytes
Vasodilation
What type of basophils secretes histamines?
Ig-E mediated
Apart from histamine, what substances are also released from basophil granules?
Heparin and proteolytic enzymes
What role do eosinophils perform?
Defence against parasites and allergic reactions.
Regulation of hypersensitivity reactions- inactivates histamine and leukotrienes
Name the precursor granulocyte cells?
Myeloblast
Promyeloblast
Metamyelocytes
Name the process in which granulocytes undergo maturation and synthesis?
Granulopoiesis
What is the distinctive pattern for myeloblasts?
Prominent nucleoli and open chromatin pattern
What is the circulating lifespan of neutrophils?
7-10 hours
What two types of substances do neutrophils secrete?
Superoxide dependent: Release of reactive oxygen species, provides enzyme substrate for myeloperoxidase
Oxygen-independent: Defensins and gelantinases
How are neutrophils identified?
Lobulated- segmented nucleus
What is chemotaxis?
The movement of a cell in the direction corresponding to a decreasing and increasing concentration gradient of a particular substance
How do neutrophils marginate and adhere themselves to the endothelium?
Selectins and integrins
Undergo polarisation, changing and rolling to a laterally suitable position for diapedesis
What is diapedesis?
Process concerning the movement of cells through intact capillary walls.
What are agranulocytes?
No lobed nuclei present
Consist of suspended granules
What are monocytes?
Responsible for the formation of macrophages; presentation of antigenic fragments
What is the function of lymphocyte B cells?
Production of antibodies
What is the function of lymphocyte T cells?
Directly attack pathogen
What is the function of macrophages?
Ingesting pathogens due to the ability of renewing lysosomes, engulfs pathogens coated with complement and antibody
Which cells give rise to lymphocytes?
Lymphoid progenitor stem cells (From multipotent haemopoietic Scs)
What are the lymphoid cells?
NK cells
T-cells
B-cells
What is the fate of lymphocyte-B cells?
Mature and differentiate into effector cells –> Plasma cells (secretion of antibodies)
Where are B-cells exposed to antigens?
Lymph nodes and lymphoid tissue
What is the role performed by T-helper cells?
Secretion of cytokines that activate B-cells (clonal selection of antibodies)
What is the role performed by cytotoxic CD8 cells?
Secretion of enzymes that compose pores in the membranes of infected cells, increases permeability of the cell-surface membrane, enabling entry of water and ions, cells burst
Where does CD4 and CD8 marker acquisition occur?
Thymus gland
What are NK cells?
Associated with the innate immune system- targets tumour cells and virus infected cells
What is neutrophilia?
High neutrophil count exceeds 7500/ microL
What causes neutrophilia?
Bacterial infection
Inflammation
Infarction
Myeloproliferative neoplasms
What drug causes neutrophilia?
Corticosteroids
What phenomenon is accompanied by neutrophilia?
Left-shift
What is left shift?
Discusses the increase in non-segmented variant neutrophils; indicative of neutrophils precursors present in the blood
Presence of band forms
What are band forms?
Non segmented neutrophils
What is neutropenia?
Decrease in the absolute neutrophil count below 1500/microL
What is agranulocytosis?
Absence of neutrophils in peripheral blood
What are the clinical causes of neutropenia?
Chemotherapy and radiotherapy
What are the causes of neutropenia?
Autoimmune disorders, severe bacterial infections (Pyogenic), drugs (anticonvulsant and antipsychotic)
What is the treatment for neutropenia?
IV antibiotics
What is hypersegmentation?
Increase in the average number of neutrophil lobes(6+) (Deficiency in B12 and Folate); megaloblastic anaemia
What is lymphocytosis?
Increase in the absolute number or proportion of lymphocytes in the blood
What are the causes of lymphocytosis?
Viral infection Epstein-Barr Virus infection Mononucleosis Leukaemia Chronic lyphocytic Whooping cough
What is basophilic cytoplasm?
Purplish patina pH? 8
What is lymphopenia?
Decrease in the absolute/proportion of lymphocytes
What are the causes of lymphopenia?
HIV
Chemo/radio therapy
Corticosteroids
What is monocytosis?
Refers to an influx in the promotion of circulating monocytes
What is eosinophillia?
Increase in the number of circulating eosinophils
What is basophillia?
Increase in the number of circulating basophils
What causes eosinophilia?
Parasitic infection
Allergy
What are the primary causes of transient and persistent leukocytosis?
Transient: Secondary cause e.g infection
Persistent: Primary blood cell disorder
What is a hypersegmented neutrophil and what causes hypersegmentation?
Right shift:
-Usually lack of folate or b12
How can you tell the difference between T/B and NK/CD8+ cells?
NK/CD8+ cells have granules
