Immunity

• Overnutrition: Inflammatory disease

  Undernutrition: Infection
• Immuno-nutrition

  • The potential to modulate the activity of the immune system by interventions w/ specific nutrients
  • Involve feeding (Enteral [Oral]/ Parenteral) enriched with pharmaconutrients [Compounds that have pharmaceutical effect in the food] to improve immune response
• Immune system

  • Body defense system that protects us against infection by harmful microorganisms (bacteria, virus) & parasites; and from development of cancer (remove mutated cells)
  • Specifically recognizes + selectively eliminates foreign invaders
  • do not attack own cells
• Origin of RBC, WBC, Platelets: Bone marrow stem cells
• B cell (Lymphocyte)

  • Mature in bone marrow
  • Reach lymph nodes/ spleen
  • Product: Antibodies, Neutralize foreign antigens
• T cells (Lymphocyte)

  • Mature in thymus
  • Product: Regulatory, Killer, Helper, Cytokines
• Macrophage (Not lymphocyte)

  • Product: Activated macrophage
• Major Lymphoid Organs and Tissues *

  • i) Primary (Central)
  • Sites for the maturation of immune system cells
  • Bone marrow (B cells); Thymus (T cells)
• Major Lymphoid Organs and Tissues

  • ii) Secondary (Peripheral)
  • Sites for the initiation of immune response
  • Where B & T cells see antigens
• Lymph nodes: found in armpits, lungs, tonsils, genital, intestine
• 2 lineages of development:

  1. Lymphoid (B, T cells)
  2. Myeloid
• Types of WBC:

  • Neutrophil
  • Lymphocytes
  • Marcrophage
  • Eosinophil
  • Basophil
• Major Effector Molecules of the Immune System (3 types)

  1. Cytokines (Cellular factors)
  2. Complement proteins
  3. Antibodies (Immunoglobulins)
• Antibody classification

  • From B cells --> activated --> Plasma cells --> see bacteria/ virus --> produce antibodies
• Complement System

  • Imp. mediator of immunity and inflammation
  • Involves > 30 diff plasma & membrane proteins
  • Mainly made by Hepatocytes & Macrophages
  • Activated by antigen-antibody complexes + Microbial polysaccharides
  • Function: Make the pathogen more visible --> Produce MAC --> Lyse foreign cells/ microorganisms + Mediate inflammation
• Cytokines

  • Peptides/ Glycoproteins (Carb + Protein); MW: 6000 – 60000
  • Produced by a wide variety of cells in the body
  • Function:

  • Involved in the regulation of cell growth + proliferation + differentiation

  • Mediator of immunity + inflammation
• Characteristics of Immune System

  1. Discrimination between Self & Non-self (Self tolerance)

  • Self = our own tissues; immune responses X altered
  • Non-self = foreign antigens; trigger immune responses

  2) High specificity and Great diversity

  • Antibodies very specific (Specifically recognize pathogens antigen)

  3) Possesses memory

  • Remember foreign antigens previously encountered; React faster 2nd time
• Functions of Immune System *

  1. Defense against infections

  • Fight against pathogenic microorganisms

  2) Homeostasis

  • Removal of aged/ damaged cells in the body
  • 3) Immunological surveillance
  • Elimination of mutated body cells
• Problems associated w/ Low Immune Function

  • Susceptibility to infections + Chronic fatigue syndrome + Cancer
• Malnutrition

  • Poor nutritional status resulting from a dietary intake below (under-nutrition: chronic undernourishment)/ above (over-nutrition) that is optimal for health
  • Caused by imbalanced nutrition
• • Overweight = BMI > 25/23
  • Obese = BMI > 30/25
• Mall-nutrition

  • A person can be overweight/ obese and still be malnourished (of micronutrients)
  • Due to having a diet consisting of high fat & sugar; low in essential vitamins & minerals
• Kwashiorkor (Protein deficiency)

  • Moderate growth retardation, Dermatitis, Edema (Low albumin), Hepatosplenomegaly (Increase weight of liver b/c need to produce more protein)
• Marasmus (Calorie deficiency)

  • Insufficiency of all foods
  • Chronic wasting, Gross underweight, Wrinkled skin with prominent facial bones
• Kwashiorkor and Marasmus both characterized by body wasting & increased susceptibility to microbial infection
• Obese ppl

  • High macrophage, mast cells, neutrophils, B cells, cytotoxic T cells (b/c inflammation)
  • Low helper T cells, regulatory T cells
• BMI = Body weight (kg)/ Body height (m2)

  • < 18.5 = Underweight
  • 18.5 – 23 = Normal
  • 23 – 25 = Overweight
  • > 25 = Obese
• Oxidative stress

  • Production of free radicals and antioxidants defense in a cell = finely balanced
  • Oxidative stress can result from

  1. Excessive production of free radicals
  2. Depletion of antioxidants
• Free radical actively looks for an electron --> Antioxidant donates an electron to a free radical --> Stabilized free radical; Antioxidant missing an electron (oxidized) but not damaging to other compounds