II. Characteristics

  1. Forms in Bone Marrow from Myeloblasts as with other Granulocytes (Neutrophils, Eosinophils, Monocytes)
  2. Basophil granules contain Heparin, vasoactive amines (Histamines, 5-Hydroxytryptamine)
    1. Released agents increase vascular permeability, allowing inflammatory agents to reach injured tissue
  3. Function: Immediate Allergic Response
    1. Similar mechanism of action to Mast Cells
    2. Related to delayed Hypersensitivity response
    3. Activated on binding IgE-Antigen complexes via high affinity receptors (FceRI)
    4. Activation results in release of inflammatory mediators contained in its secretory granules
      1. Immediate release of preformed mediators (e.g. Histamine, Bradykinin) within first 5 minutes
      2. Leukotriene C4 released within 5-30 minutes, and results in bronchoconstriction
      3. Releases Cytokines TNF-alpha and IL4 within hours
      4. Chemotactic factors attract Neutrophil, Eosinophil

III. Labs: Morphology on Blood Smear

  1. Granulocyte cytoplasm stains darkly with Wright Stain
  2. Two lobed nucleus
  3. Diameter: 5-7 microns

IV. Interpretation: Normal Levels

  1. Range: 0.4-1.0% (Least common Leukocyte)

V. Causes: Increased Basophils (Basophilia)

  1. Viral Infections (e.g. Varicella)
  2. Hodgkin's Lymphoma
  3. Hemolytic Anemia
  4. Following splenectomy
  5. Myeloproliferative disease
    1. Chronic Myelogenous Leukemia
    2. Polycythemia Vera
    3. Myelofibrosis
  6. Inflammatory processes
    1. Inflammatory Bowel Disease
    2. Chronic dermatitis
    3. Asthma
    4. Chronic Sinusitis
  7. Endocrine causes
    1. Hypothyroidism
    2. Increased Estrogen

VI. Causes: Decreased Basophils

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