White Blood Cells (WBCs), also called leukocytes, are defensive cells of the immune system that protect the body against infections, foreign particles, and diseases.
📍 Origin
- Produced in bone marrow
- Mature in lymphoid organs (lymph nodes, spleen, thymus)
⏳ Life Span of Different Types of WBCs
1️⃣ Neutrophils
- Life span: Few hours to 1–2 days
- Most abundant WBC
- Function: First line of defense, destroy bacteria and fungi
2️⃣ Lymphocytes
- Types: T-cells, B-cells, NK cells
- Life span: Few weeks to several years
Function:
- T-cells: Cell-mediated immunity
- B-cells: Antibody production
Longest living WBCs
3️⃣ Monocytes
- Life span in blood: 1–3 days
- In tissues: Several months
- Convert into macrophages
- Function: Phagocytosis (engulf pathogens and dead cells)
4️⃣ Eosinophils
Life span: Few days to 2 weeks
Function:
- Fight parasitic infections
- Involved in allergic reactions
5️⃣ Basophils
- Life span: Few days
- Least common WBC
Function:
- Release histamine and heparin
- Involved in allergy and inflammation
📊 Table Summary for Students
| WBC Type | Approximate Life Span |
|---|---|
| Neutrophils | Hours – 2 days |
| Lymphocytes | Weeks – Years |
| Monocytes | Months (in tissues) |
| Eosinophils | Days – Weeks |
| Basophils | Few days |
🧠 General Knowledge (GK) Points
- WBCs are nucleated cells
- Normal WBC count: 4,000–11,000 / µL of blood
- Short life span = quick immune response
- Long life span = long-term immunity (memory cells)
- Lymphocytes are responsible for immunological memory
MCQs Online Test — Life Span of WBCs
Q1. Which WBC has the longest life span?
A. Neutrophils
B. Eosinophils
C. Monocytes
D. Lymphocytes ✅
Q2. The life span of neutrophils is:
A. Several years
B. Several months
C. Few hours to 1–2 days ✅
D. Few weeks
Q3. Which WBC changes into macrophages in tissues?
A. Lymphocytes
B. Neutrophils
C. Monocytes ✅
D. Basophils
Q4. WBCs involved in allergic reactions are:
A. Neutrophils
B. Basophils & Eosinophils ✅
C. Lymphocytes
D. Monocytes
Q5. Which WBC is responsible for antibody formation?
A. T-lymphocytes
B. B-lymphocytes ✅
C. Neutrophils
D. Monocytes
Q6. Which WBC has the shortest life span?
A. Monocytes
B. Lymphocytes
C. Neutrophils ✅
D. Eosinophils
Q7. White blood cells are also called:
A. Erythrocytes
B. Thrombocytes
C. Leukocytes ✅
D. Macrophages
📚 Exam Tip
Neutrophils = shortest life
Lymphocytes = longest life
(very common MCQ in Biology, MDCAT, FSC, and Nursing exams)
