Immune - Paper <=1998
1998_2nd
semester_Q2_Part_B
i.
Inflammation is an observable non-specific response which is involved
whenever tissue damage, or injury occurs as a result of physical, chemical or
pathogenic activity. The cardinal signs of inflammation are redness, swelling,
pain and heat. The combined factors normally cause impaired function of the
affected area.
The
events that characterize the cardinal signs are as follows. The redness, heat
and pain and swelling are all a result of increased vasodilation of the blood
vessels in that area, and increased vascular permeability. This causes increased
amounts of blood to perfuse through this region, causing the redness, and due to
this lots of fluid moves into the interstitial space causing the swelling.
Swelling of the area, compresses surround nerves causing the pain. The heat is
associated with the increased supply of blood. After this, migration of the
phagocytic cells mentioned above occurs, and they phagocytose cell debris and
foreign substances. This is due to the chemotactic attraction of phagocytes to
the inflamed area. Following this, tissue repair begins.
ii.
The agents that are involved in the inflammation response are mainly
macrophages, white blood cells particular monocytes and neutrophils as they have
phagocytic properties, mast cells and natural killer cells. Macrophages and
other phagocytic cells engulf the foreign substance, whereas natural killer
cells kill of the virus infected and tumor cells and stop the spreadage of the
disease.
During inflammation several chemical mediators are involved, that are released and amplify the inflammatory response. These are histamine which is released by damaged mast cells, basophils and platelets. Leukotrienes are largely derived from membrane lipids of basophils and mast cells. Kinins are another variety which are found in inactive forms in the plasma and also released by neutrophils. Prostaglandins are derived from membrane lipids of damaged cells and neutrophils. All four mediators have an effect on the vascular changes that occur during inflammation, the last three have an effect on the chemotactic attraction of phagocytes to the inflamed area and the last two mediate the pain caused during inflammation.
1997_2nd
semester_Q3_Part_B
Immunological
Memory
v
Concept that the immune response can recognise same antigens if they
reappear
v
Provided by memory b cells and t cells which are derived during the
co-stimulation stage after proliferation of t helper cells occurs in both
humoral and cell mediated immunity
v
The second response to an antigen is normally, larger, more prolonged,
faster, and more destructive than the first
v
Draw a graph explaining the relative response rates and depths
v
Concept on which vaccinations are based on
T
lymphocytes
v
One of the types of lymphocytes available which originate in bone marrow
v
Migrate to the Thymus (i.e.: thymus depended lymphocytes) where they
undergo strict “training” to detect antigens
v
Normally migrate throughout their life
v
Two types: cytotoxic t cells, helper t cells and memory t cells
v
Cytotoxic cells are involved in cell mediated immunity and directly
attack the antigens, helper t cells assist in stimulation activation of b cells
in humoral immunity and Cytotoxic t cells in cell mediated immunity
v
Memory t cells have specific receptors a specific antigen and can respond
to entry of this antigen into the body – important in concept of Immunological
memory.
Inflammation
v
Cardinal signs are redness, swelling, heat and pain which cause impaired
function of the affected area
v
Agents involved are macrophages, white blood cells (neutrophils and
monocytes), mast cells and natural killer cells
v
Events involved are vasodilation, increased vascular permeability,
migration (due to chemotactic attraction of phagocytes to the inflamed area),
phagocytosis, tissue repair, release of chemical mediators
v
Chemical mediators include, histamine,
leukotrienes, kinins, prostaglandins each having a specific function/s
v
Best treatment for inflammation is REST, ICE, COMPRESSION AND ELEVATION
Lymph
v
Substance which is formed in extracellular tissues and is taken in by
lymphatic vessels
v
Lymphatic vessels begin as blind ended tubes, have incompletely sealed
edges which allow for valves (prevent backflow of lymph), have anchoring
filaments which provide structural integrity to the vessels
v
Lymph is a mixture of proteins, water, and mostly white blood cells
v
Flows into collecting ducts which then flow back into the venous
circulation via the lymphatic ducts (mainly to subclavian and internal jugular
vein).
v Is produced as a result of imbalance between the hydrostatic pressure within blood capillaries and plasma oncotic pressure within extracellular tissues.
1996_2nd
semester_Q3_Part_B
A
specific immune response occurs when a particular antigen has gained entry into
the body tissues. There are two types of specific immune response, one which is
humoral immunity and the other is cell mediated immunity. Humoral immunity
involved the synthesis and secretion of antibodies which bind to antigens to
neutralise, agglutinate them. Cell mediated immunity involved direct cell to
cell contact to kill of the antigens. The main difference between the two is
that the former is based on targets involving extracellular antigens (i.e.:
circulating in blood, connective tissue or lymph) and the latter is based on
antigens within tissues (where antibodies cannot get access to).
Antigens
are substances that trigger an immune response and these are generally large
molecules. They have a specific portion which causes this response and this is
referred to as the hapten. The fundamental basis of a specific immune response
is the presence of antigens. This triggers special dendritic cells called
antigen presenting cells to engulf these antigens and partially digest them,
leaving only the hapten portion sticking outside. This then combines with the
MHC-II proteins present on the antigen presenting cells. Circulating t helper
cells bind to these complexes if they have receptors to the antigens and this
triggers the release of cytokines, which are substances which cause the
proliferation and differentiation of other cells. In this case, the t helper
cells proliferate and differentiate and this co-stimulates the proliferation of
either b lymphocytes in the case of humoral immunity or cytotoxic t cells. B
lymphocyes then become plasma cells or memory b cells, and the secretion of
antibodies is evident in plasma cells. Cytotoxic t cells go on to attack the
antigen by direct cell to cell contact.
Antibodies
secreted by the plasma cells have a special structure. There are several class
of antibodies namely: IgM, IgA, IgD, IgG, IgE. These all have the same antigenic
specificity and are formed in different circumstances. Antibodies structurally
are made of two light polypeptide chains and two heavy polypeptide chains. The
antibody can bind to a specific antigen, but because there are two arms, due to
Y shape exhibited, they can bind to two antigens. The stem of the antibody is
recognised by macrophages and other phagocytic cells, and these engulf the
antigen-antibody complex formed.
Major Points: Two types of specific immune response > What causes these immune response (i.e.: antigens) > What are antigens, specific hapten structure > What are the products of each type of response (i.e.: antibodies and cytotoxic t cells) > structure of antibodies --. Classes of antibodies > function of antibodies
1995_2nd semester_Q3_Part_B
Passive
Immunity
v
A type of humoral immunity
v
Involves passively giving antibodies to another person either naturally
(i.e.: breast feeding), or artificially (i.e.: serum)
Complement
v
Special group of plasma proteins found in plasma
v
Can be activated by the presence of bacteria
v
One activated complement can activate another complement following a
chemical cascade
v
Can form clumps and then forming membrane attack complexes which lyse the
cell membranes of foreign substances
See
above answers for other answers to these questions.