Makindo Medical Notes

Related Subjects: |Red blood cells |White blood cells |Lymphocytes |Platelets |Cryoprecipitate |Fresh Frozen Plasma |Blood Cell Maturation

🩸 White blood cells (WBCs), or leukocytes, are vital defenders of the immune system. They protect the body against infections and foreign invaders. Produced in the bone marrow, WBCs circulate in the blood and lymphatic system, with different subtypes playing distinct roles in immune defence.

🧬 Types of White Blood Cells

• Neutrophils 🔥
  • 12–15 μm, segmented nucleus (2–5 lobes).
  • First responders in acute inflammation.
  • Key role: phagocytosis of bacteria & fungi.
  • Normal range: 40–60% of WBC count.
• Eosinophils 🪱
  • 12–15 μm, bilobed nucleus.
  • Large orange granules (contain Major Basic Protein).
  • Defend against parasites; active in allergies.
  • Normal range: 0–6%.
• Basophils 🌸
  • 12–15 μm, coarse purple-black granules.
  • Granules contain histamine & heparin → hypersensitivity reactions.
  • Normal range: 0–1%.
• Monocytes 🛡️
  • 12–20 μm, kidney-shaped nucleus.
  • Differentiates into macrophages in tissues → chronic inflammation, phagocytosis.
  • Normal range: 0–10%.
• Lymphocytes 🎯
  • 7–20 μm; subtypes = T cells, B cells, NK cells.
  • Adaptive immunity: antibody production & cytotoxic defence.
  • Normal range: 20–40%.

📈 Causes of a Raised WBC Count (Leukocytosis)

• Leukaemias: AML, ALL, CML, CLL
• Lymphoma, myeloma, myelofibrosis
• Infections (bacterial, viral, fungal, parasitic)
• Corticosteroid therapy
• GI bleeding (acute/brisk)
• Stress (e.g. post-surgery)
• Post-splenectomy

📉 Causes of a Low WBC Count (Leukopenia)

• Bone marrow suppression (chemo, radiation, toxins)
• Aplastic anaemia
• Viral infections (HIV, hepatitis)
• Severe sepsis (overwhelmed marrow)
• Autoimmune disease (e.g. SLE)
• Nutritional deficiency (B12, folate)
• Prolonged steroid use

🔎 Subgroup-Specific Causes of Raised WBCs

• Neutrophilia 🔥 → bacterial infection, RA, trauma, burns, steroids, CML
• Eosinophilia 🪱 → allergy (asthma, hay fever), parasites, EGPA, Hodgkin’s lymphoma
• Basophilia 🌸 → CML, urticaria, hypothyroidism, chronic inflammation
• Monocytosis 🛡️ → chronic infections (TB, syphilis), lupus, myelodysplasia
• Lymphocytosis 🎯 → viral infections (EBV, hepatitis), CLL, lymphoma, autoimmune

🚨 Worrying Features Suggesting Malignancy

• Signs of sepsis or severe infection
• Bleeding, bruising, petechiae (cytopenias)
• Hepatosplenomegaly or lymphadenopathy
• Unexplained weight loss
• Abnormal blood film findings

📚 References

• University of Virginia Teaching Site