Leukocytes and Chemotherapy Effects

Leukocytes

• Lymphocytes
  • 20%-45% of white blood cell count
  • T cells and B cells
  • Development: Days to weeks
  • Life Span: Hours to years
  • Function: Mount immune response by direct cell attack (T cells) or antibodies (B cells)
• Monocytes
  • 4%-8% of white blood cell count
  • Development: 2-3 days
  • Life Span: Months
  • Function:
    • Phagocytosis
    • Develop into macrophages in tissues

Leukopenia During Chemotherapy

• Cancerous cells grow faster than normal cells
• Chemotherapy targets fast-growing cells by interrupting mitotic cell division
• Chemotherapy also kills a few normal fast-growing cells, including:
  • Leukocytes
  • Hair
  • Intestinal epithelial cells

Erythrocytes (Red Blood Cells, RBCs)

• Average: 5 million/mm3
• Appearance: Biconcave disc shape, suited for gas exchange. The shape is flexible so that RBCs can pass through capillaries.
• Structure:
  • Primarily made up of hemoglobin (protein that binds oxygen and carbon dioxide)
  • Lack a nucleus and mitochondria

Hemoglobin

• Consists of four protein chains (globins) and four heme groups
• Heme groups: Nonprotein moiety that binds O2 to ferrous ion (Fe2+) at its center
• Globins: Four protein chains - two alpha and two beta chains

Plasma Proteins

• Site of formation: Liver
  • Albumin: 3.5-5.0 gm/dL, 50% in the liver and 50% in white blood cells
  • Globulins: 2.5 gm/dL
  • Fibrinogen 0.4 gm/dL
  • Prothrombin: 0.01 gm/dL

Specific Functions of Plasma Proteins

• Albumin:
  • Maintains osmotic pressure
  • Transports smaller molecules (hormones, ions)
• Globulins:
  • Alpha and Beta globulins transport hormones and fat-soluble vitamins
  • Gamma globulins (antibodies) bind to foreign substances
• Fibrinogen: Converted to fibrin network that forms blood clots
• Prothrombin: Blood clotting

Plasma vs Serum

• Plasma: Blood fluid containing clotting factors
• Serum: Plasma lacking some clotting factors

Leukocytes (White Cells)

• Two major categories:
  • Granulocytes: Contain specialized membrane-bound cytoplasmic granules (neutrophils, eosinophils, and basophils)
  • Agranulocytes: Lack obvious granules (lymphocytes and monocytes)

Neutrophils

• 40%-70% WBCs
• Development: 6-9 days
• Life Span: 6 hours to a few days
• Function: Phagocytize bacteria

Eosinophils

• 1%-4% WBCs
• Development: 6-9 days
• Life Span: 8-12 days
• Function: Kill parasitic worms

Basophils

• 0.5% WBCs
• Development: 3-7 days
• Life Span: A few hours to a few days
• Function: Release histamine and other mediators of inflammation

Functions of RBCs

• Carry hemoglobin
• Transport oxygen
• Transport carbon dioxide
• Buffer (pH regulation)

RBC Counts

• Males: 4.8-5.8 million cells/mm3
• Females: 4.2-5.2 million cells/mm3

RBC Life Span

• 120 days

Erythropoiesis

• The process of RBC formation

ABO Blood Group System

• The ABO blood group system categorizes human blood based on the presence or absence of specific antigens (A and B) on red blood cells.
• There are four main blood types:
  • Type A: Contains antigen A and antibody B in the plasma.
  • Type B: Contains antigen B and antibody A in the plasma.
  • Type AB: Contains both antigen A and antigen B, but no antibodies against A or B.
  • Type O: Contains neither antigen A nor antigen B, but has both antibody A and antibody B in the plasma.
• Blood type inheritance is determined by two alleles (A and B) and a recessive allele (O):
  • AA or AO: Type A
  • BB or BO: Type B
  • AB: Type AB
  • OO: Type O
• Matching ABO blood types during blood transfusions is crucial to prevent potentially fatal hemolytic reactions.
• In pregnancy, ABO incompatibility between mother and fetus can cause hemolytic disease of the newborn (HDN).

Rh Factor

• The Rh factor is a protein (D antigen) that can be present on the surface of red blood cells.
• Individuals with the D antigen are Rh positive (Rh+), while those without it are Rh negative (Rh-).
• Rh factor inheritance is independent of the ABO system with Rh positivity being dominant over Rh negativity.
• Matching Rh types during transfusions is essential to avoid complications. Rh- individuals who receive Rh+ blood can develop antibodies, posing risks for future transfusions.
• In pregnancies where an Rh- mother carries an Rh+ fetus, Rh incompatibility can occur, leading to HDN.
• Administration of Rh immunoglobulin (Rho(D) immune globulin) to Rh- mothers prevents the development of antibodies.