IS

• IMMUNOLOGY - study of a host's reaction when foreign substances are introduced into the body
• ANTIGEN - foreign substances that induce an immune response
• roots in the study of immunity, wherein it is the condition of being resistant to infections
• IMMUNE SYSTEM PRIMARY FUNCTION

  • surveillance and destruction of substances that are foreign to the body
• IMMUNE SYSTEM

  • recognize self from nonself
  • defend body from nonself
• IMMUNE SYSTEM IS DIVIDED INTO - innate and adaptive immunity
• INNATE AND ADAPTIVE IMMUNITY ARE SUBDIVIDED INTO - HUMORAL and CELLULAR immunity
• HUMORAL IMMUNITY

  • deals with the substances usually PROTEINS that are present in the BODY FLUIDS
• CELLULAR IMMUNITY

  • cellular aspect of immunity that deals with CELLS
• DIVISION OF IMMUNITY IS JUST FOR ACADEMIC PURPOSES
• INNATE IMMUNITY

  • anatomical, cellular and humoral defenses
  • ability to RESIST INFECTION by means of NORMALLY PRESENT BODY FUNCTIONS
  • considered NON-ADAPTIVE or NONSPECIFIC
  • Response is SAME FOR ALL PATHOGENS after exposure
• INNATE IMMUNITY composed of

  • external defense system
  • internal defense system
  • humoral factors
  • cellular defense
• EXTERNAL DEFENSE SYSTEM - designed to keep microorganism from entering the body

  • structural barriers that PREVENT MOST INFECTIOUS AGENT FROM ENTERING THE BODY
  • the defense mechanism has NO SPECIFICITY and LIMIT THE ENTRY OF ALL PATHOGENS
• EXAMPLE OF EXTERNAL DEFENSE SYSTEM

  • structural barriers
  • anatomical barriers - skin, mucous membranes, cilia (RESPIRATORY TRACT EPITHELIUM), resident flora (NON-PATHOGENIC BACTERIA)
• INTERNAL DEFENSE SYSTEM

  • CELLS and SOLUBLE factors play an essential part
  • designed to RECOGNIZE molecules that are UNIQUE TO INFECTIOUS ORGANISM
  • IMMUNOLOGIC SUBSTANCES that are PRESENT in BODY FLUIDS
  • can be categorized to HUMORAL and CELLULAR factors
• HUMORAL FACTORS

  • LYSOZYME - present in TEARS, SEBACEOUS, AND SWEAT GLANDS secretions that will CLEAVE the cell wall of bacteria
• LACTOFERRIN - BINDS IRON, an essential growth molecule for bacteria restricting the amount of iron essential for growth of bacteria
• PEPSINS - PRESENT IN STOMACH, digest BACTERIAL SURFACE PROTEIN and would bind to cells that are present in the INTESTINAL LAMINAE
• STOMACH ACIDITY - provide HOST DEFENSE because organisms cannot survive the acidic environment of stomach
• COMPLEMENT - MADE UP OF family of proteins (around 30 proteins) that leads to the destruction of microorganisms

  • present in BLOOD, LYMPH, AND INTERSTITIAL FLUID
• OPSONINS - proteins that FACILITATE PHAGOCYTOSIS
• CELLULAR DEFENSE

  • CELLS THAT ARE PRESENT IN THE BONE MARROW
  • RECRUITED WHEN INITIAL BARRIERS HAVE BEEN BREACHED
• CELLS OF INNATE IMMUNITY CONSISTS PRIMARILY OF

  • PHAGOCYTES
  • NATURAL KILLER CELLS
  • EOSINOPHILS
  • ANTIGEN PRESENTING CELLS
  • MAST CELLS
  • BASOPHILS
• PHAGOCYTES - engulf and destroy foreign substances and microorganisms
• NATURAL KILLER CELLS - eliminate VIRALLY INFECTED CELLS
• EOSINOPHILS - ELIMNATES HELMINTHS
• ANTIGEN PRESENTING CELLS (APC) - PRESENTING CELLS WILL PROCESS ANTIGENS

  • present the antigenic fragments from processing to one group of cells that will function in ADAPTIVE IMMUNE SYSTEM
• MAST CELLS AND BASOPHILS

  • release substances that facilitate recruitment of immune cells to site of infection
• MYELOID PRECURSORS WILL GIVE RISE TO

  • NEUTROPHILS
  • MONOCYTES
  • BASOPHILS
  • EOSINOPHILS
• LYMPHOID PROGENITOR CELLS

  • give rise to NATIVE MATURE B CELLS - cells that have not been ANTIGENICALLY STIMULATED
• PRECURSOR T CELLS

  • FULL DIFERRENTIATION OCCURS IN THYMUS
• immune cells undergo MATURATION, DIFFERENTIATION, AND PROLIFERATION
• BURSA OF FABRIO- first determined site of B CELL MATURATION
• BONE MARROW - SITE OF B LYMPHOCYTES MATURATION IN HUMANS
• PRIMARY LYMPHOID ORGANS - SITE WHERE PROGENITOR CELLS WILL DIFFERENTIATE INTO T AND B CELLS
• CELLS IN PRIMARY LYMPHOID TISSUE DOES NOT COME IN CONTACT WITH FOREIGN ANTIGEN
• BONE MARROW (B CELLS)

  • MATURATION OF B CELLS
• HEMATOPOIESIS happens in BONE MARROW and is the site where aspects of maturation occurs
• key feature of B CELL MATURATION - rearrangement of genes that encode receptor that will recognize foreign antigen BUT NOT SELF MOLECULES
• RECEPTORS - are membrane bound antibodies; often referred to as MEMBRANE IMMUNOGLOBULINS