Immune Flashcards
Functions of the immune defenses
-protection against infection
-removal of non-microbial foreign substances
-destruction of cancer cells that may arise
Innate immune response
non-specific response to pathogens
-carbohydrates and lipids
-same cells react to many invaders
Adaptive immune response
highly specific response to pathogens that refines over time
-specific proteins
-slower development
-VERY specific
-Wide variety of pathogens
-relies on B and T cells
white blood cells
-cells of the immune system that circulate in the blood and lymphatic system
-fast and mobile
-protect body against invading microorganisms and cells with mutated DNA
-clean up debris
Myeloid cells
neutrophils
basophils
eosinophils
monocytes
Lymphoid cells
T&B lymphocytes
natural kill cells
plasma cells
B & T cells
derived from stem cells and bone marrow
Three stages of adaptive immune response
- encounter and recognition of an antigen by lymphocytes
- lymphocyte activation
- attack launched by activated lymphocytes and their secretions
primary lymphoid organs
-initial sites of lymphocyte development
-supply secondary lymphoid organs
bone marrow
thymus with mature but naive lymphocytes
-BONE MARROW & THYMUS
Secondary lymphoid organs
-organs in which naive lymphocytes are activated
-participate in adaptive immune responses
-SPLEEN, LYMPH NODES, TONSILS, LININGS OF GI/RESP/GU TRACTS
B-cell receptors
identical to unique antibodies secreted by plasma B-cells
-bind to antigens
Immunoglobulin (Ig)
2 long chains & 2 short chains
classes of immunoglobulin
IgA
IgD
IgE
IgG
IgM
Class 1 MHC proteins
found on almost all cells of the body except erythrocytes
Class II MHC proteins
mainly on the surface of macrophages, B cells, and dendritic cells
Helper T-Cell
-secrete cytokinesis to activate other cells
-require antigens bound to Class II MHC proteins in order to recognize them
Antigen-presenting cells (APCs)
found on B-cells, macrophages, and macrophage-like cells
3 things required to activate helper T cells
- presentation of antigens
- contribution of a co-stimulus
- secretion of cytokines (IL-1 & TNF)
Cytotoxic T cells
Directly destroys the body cells that have become cancerous or infected with viruses
Natural killer cells
*non-antigen specific
-no T-cell receptors or Ig receptors
-no MHC proteins
-attack virus-infected or cancer cells without recognizing a specific antigen
Memory cells
-come from B cells
Plasma cells
secrete antibodies specific for the antigen that initiated the response
Antibodies
combine with the antigen on the surface of the bacteria anywhere in the body
Phagocytosis
-neutrophils & macrophages
facilitated in the presence of antibody bound to antigen
Complement system
enhances phagocytosis and can directly kill the bacteria
cellular toxicity
mediated by NK cells
-bind to the antibody’s Fc portion
IgG
gamma globulins
-most abundant
-only ones to cross placenta
IgM
specific immunity in extracellular fluid
-primary immune response
IgE
allergic responses
-also parasitic infections
IgA
linings of GI, resp, GU tracts, mammary glands
IgD
function not yet known
Attack effect of antibodies
-enhanced phagocytosis
-activates complement system
-cellular cytotoxicity
-direct neutralization of bacterial toxins and viruses
antibody production
-occurs slowly after first contact (several weeks)
-immediate response after subsequent infection
key feature distinguishes innate and adaptive immunity
adaptive is mediated by memory B cells
Active immunity
resistance built up as a result of the body’s contact with microorganisms and their toxins
-infection or vaccine
Passive immunity
direct transfer of antibodies from one person to another
-IgG through placenta
-IgA through breastmilk
-Gamma globulin injections
How are macrophages and NK cells activated?
activated helper T cell secretes IL-2 and interferon-gamma which activated macrophages and NK cells which then secrete cell-killing chemicals
greatest contributor to decreased resistance
protein-calorie malnutrition
factors related to decreased infection resistance
-protein-calorie malnutrition
-preexisting disease (HIV/AIDS)
-sleep deprivation
-anti-rejection meds
-stress
*modest exercise benefits immune system
Graft rejection
immune system recognizes the transplants as foreign and launches an attack against them
transfusion reaction
erythrocytes have ABO carbohydrates that act as antigens
-antibodies to opposite antigens circulating in the blood
-Rh reactions happen like classic immunity, not from already present antibodies
Interleukin 1
Source: antigen presenting cells
Target: Helper T cells
Function: stimulate IL-2 release, induce fever, systemic response
Interleukin 2
Source: most immune cells
Target: both T cells, NK cells, B cells
Function: stimulate proliferation, conversion to plasma cells
