Immunology 4: Attributes of the Immune System

Question 1

Humoral immunity

Answer 1

• soluble antibodies present in immune system
• its effects can be transferred to unimmunized animals by transfer of immune animals serum
• Metchnikoff advocated importance of cells in immunity

Question 2

Who said “it struck me that similar cells might serve in the defence of the organism against intruders”?
What did he do after this idea came to him?

Answer 2

Metchnikoff

• same day as this idea, he inserted thorn into transparent larva of starfish & examined it next day to find the thorn surrounded by mobile cells with ability to take/digest foreign matter (phagocytes)
• likened them to amoebae

Question 3

Metchnikoff suggested macrophages are ___.

Answer 3

mediators of natural/innate resistance!
-early studies proved resistance to most pathogens/toxins was because of humoral immunity (since cell-free immune serum could confer protection once transferred)

Question 4

Cell-mediated immunity

Answer 4

Resistance against some pathogens can be achieved by immunization, but cannot be transferred like in humoral.
-cells essential elements needed for resistance

Question 5

Example of distinction between cell-mediated & humoral immunity

Answer 5

Tuberculosis pathogen (Mycobacterium tuberculosis)
-antibodies cannot kill this pathogen, cell-mediated immunity can

Question 6

Immediate-type hypersensitivity

Answer 6

immunization with antigen leads to state where acute inflammation elicits within minutes of antigen injection in the skin

Question 7

Delayed-type hypersensitivity

Answer 7

-maximum inflammation between 24-72h after antigen application

Question 8

Since allergic state to an antigen can be transferred via immune serum transfer _____.

Answer 8

Antibodies are responsible for allergic state (humoral immunity)
-for delayed type hypersensitivity, sensitivity is only transferred by cells thus, delayed hypersensitivity is expression of cell mediated immunity

Question 9

Administration of virtually any foreign matter into a vertebrate provokes ___

Answer 9

Immune response

• a mouse’s serum almost always contains antibodies to injected antigen during experiment (know because of precipitin reaction)
• this reflects universality of immune system

Question 10

Can we live without innate defence mechanisms?

Answer 10

NO

-immune systems takes days to happen, by then bacteria would be so replicated we’d die before it could activate

Question 11

Antibodies are very ___.

Answer 11

Specific

Question 12

Specificity & universality of immune responses means ____.

Answer 12

Many different antibodies

• key & lock
• many locks, so many keys

Question 13

Self-nonself discrimination of immune system

Answer 13

-ability to respond to foreign but not self molecules/cells.

Paul Ehrlich, 1901
-if we attack own cells, integrity of host would be destroyed (autoimmune diseases) so must be mechanism to prevent immune reactivity to self molecules/cells

Question 14

Classes of antibodies

Answer 14

Many induced under diff conditions

• IgE’s (bind to mast cells, cause histidine release & acute inflammation response *allergies)
• IgM
• IgG
• IgA

Question 15

Possibility that immune responses differentially regulated?

Answer 15

many different classes of antibodies/immunity indicates so

-causes immunization that induces cell mediated immunity often fails to induce antibody response (& vice versa).