WBC and Platelets

• What are leukocytes commonly known as?

  White Blood Cells
• Why are leukocytes referred to as white blood cells?

  They are relatively colorless compared to RBCs
• What are the two types of leukocytes?

  • Granulocytes
  • Neutrophils
  • Eosinophils
  • Basophils
  • Agranulocytes
  • Monocytes
  • Lymphocytes
• What is the reference range for leukocyte count?

  4.5 to 11.5 x 10^9/L
• What is the primary function of leukocytes?

  Immunity through phagocytosis and antibodies
• What does kinetics refer to in the context of leukocytes?

  Movement of cells through developmental stages
• What is the size range of myeloblasts?

  14 to 20 µm in diameter
• What is the nuclear-to-cytoplasmic ratio of myeloblasts?

  N:C ratio of 8:1 to 4:1
• What is the size range of promyelocytes?

  16 to 25 µm in diameter
• What is a distinguishing feature of normal promyelocytes?

  A paranuclear halo or hof is usually seen
• How can eosinophilic promyelocytes be identified?

  Presence of Charcot-Leyden crystal protein
• What percentage of nucleated cells in the bone marrow are myelocytes?

  6-7% of nucleated cells
• What occurs during the myelocyte stage?

  Begins to manufacture secondary granules
• What is the percentage range of metamyelocytes in nucleated marrow cells?

  3% to 20% of nucleated marrow cells
• What shape is the nucleus of a metamyelocyte?

  Kidney bean shaped or peanut shaped
• What percentage of nucleated marrow cells are bands or juvenile cells?

  9 to 32% of nucleated marrow cells
• When are bands or juvenile cells elevated?

  In patients with infection
• What percentage of nucleated cells in the bone marrow are segmented neutrophils?

  7 to 30% of nucleated cells
• How many nuclear lobes do segmented neutrophils have?

  2-5 nuclear lobes
• What are the primary functions of segmented neutrophils?

  Phagocytosis and destruction of foreign material
• What percentage of nucleated cells in the bone marrow are eosinophils?

  1 to 3% of nucleated cells
• What percentage of leukocytes do segmented neutrophils comprise?

  50% to 70% of leukocytes
• What is the function of eosinophils?

  Immune regulation and destruction of helminths
• What is the function of basophils?

  Initiators of allergic inflammation
• What percentage of circulating leukocytes are basophils?

  0-2% of circulating leukocytes
• What role do basophils play in angiogenesis?

  Expression of vascular endothelial growth factor
• What percentage of circulating leukocytes do monocytes make up?

  2% to 11% of circulating leukocytes
• What cytokine influences monocyte growth and differentiation?

  M-CSF
• What are the functions of monocytes/macrophages?

  1. Innate Immunity

  • Pattern recognition receptors stimulate cytokines

  1. Adaptive Immunity

  • Present antigen fragments on their surface

  1. Housekeeping

  • Remove debris and dead cells
• How do lymphocytes differ from other leukocytes?

  1. Not end cells; undergo mitosis when stimulated
  2. Recirculate from blood to tissues and back
  3. Capable of rearranging antigen receptor genes
  4. T and NK lymphocytes mature outside bone marrow
• What are the two types of immunity lymphocytes participate in?

  1. Cellular immunity (T-cells and NK cells)
  2. Humoral immunity (B-cells)
• What are the stages of B and T cell development?

  1. Antigen-independent (in BM and Thymus)
  2. Antigen-dependent (in spleen, lymph nodes, etc.)
• What are the stages of B-cell development in the bone marrow?

  Pro-B cells, Pre-B cells, Immature B cells
• What happens when immature B-cells contact an antigen?

  They produce memory and effector cells
• What percentage of circulating lymphocytes are B cells?

  Approximately 3% to 21%
• What is the role of lymphoid progenitors in T-cell development?

  Migrate from BM to Thymus for maturation
• What are the stages of T-cell development?

  1. Pro-T cells in the Thymus
  2. Maturation occurs in the Thymus
• What are the two types of lymphocyte development?

  Antigen-independent and antigen-dependent
• Where does antigen-independent lymphocyte development occur?

  In the bone marrow and thymus
• Where does antigen-dependent lymphocyte development occur?

  In spleen, lymph nodes, and tonsils