Immunology

Question 1

What are the characteristics of the INNATE immune system?

Answer 1

Immediate response to generalized pathogens

Components/defense mechanisms include inflammation, fever, skin, mucous membranes, gastric juices, saliva and urine, as well as some cytokines, phagocytes and natural killer (NK) cells.

Question 2

What are the characteristics of ADAPTIVE immunity?

Answer 2

Slower response built post-exposure, specific to an antigen, improves with each exposure.

Components/defense mechanisms: T&B lymphocytes, macrophages, antibodies, cytokines and complement system

Question 3

Describe phagocytosis

Answer 3

Starts with chemotaxis attracting phagocytes to cells. Adherence of phagocyte to antigen happens via complement protein system. The pseudopods of the phagocyte envelops the pathogen, and it’s brought into the cell as a capsule where it’s killed and digested.

Question 4

Phase 1 and Phase 2 of inflammatory response

Answer 4

Phase 1: vasodilation, increased permeability and nitric oxide release causes redness, pain, heat and swelling.

Phase 2: leukocytes move to site of infection, attracted by cytokines; phagocytosis and adaptive response begins.

Question 5

Which white blood cells are part of the INNATE immune response?

Answer 5

Leukocytes: they develop into neutrophils, eosinophils, basophils, mast cells, dendritic cells, macrophages or monocytes.

Question 6

Which is the most plentiful WBC?

Answer 6

Neutrophils: they phagocytose pathogens then “suicide bomb” them via oxidative process

Question 7

Which WBC is the basis of the ADAPTIVE immune response?

Answer 7

Lymphoid cells: they mature into natural killer cells, B or T cells

Question 8

Characteristics of B cells

Answer 8

Mature in bone marrow.
B cells can directly bind to an antigen (vs. needing an antigen presenting MHC), and secrete antibodies that mark pathogens for destruction.

Question 9

Characteristics of T cells

Answer 9

Mature in the thymus.

T cells secrete cytokines and can identify specific antigens on MHC. They are cytotoxic

Question 10

What are cytokines?

Answer 10

“Hormones of the immune system”, 5 types:

1) Interlukens attract other immune cells to site of inflammation, as well as encourage immune cell division
2) TNF increase vascular permeability and induce fever
3) Interferons degrade mRNA in infected cells, and “interfere” (get it?) with viral replication
4) Colony stimulating cause stemm cells to differentiate into granulocytes
5) TGF controls proliferation, plays a role in slowing down the immune response.

Question 11

What is the difference between Helper and Cytotoxic T Cells?

Answer 11

Helper T’s are CD4 positive. They coordinate the adaptive immune response and instruct B cells to secrete a specific antibody.

Cytotoxic T cells (CD8 positive) do the killing.

Question 12

What are the main lymphatic organs?

Answer 12

Red bone marrow and thymus, where stem cell division occurs.

Question 13

What are secondary lymphatic organs?

Answer 13

Lymph nodes, spleen and lymphatic nodules found in tonsils, appendix and throghout the body.

Question 14

Describe humoral immunity

Answer 14

B cells engulf an antigen, and it is broken into fragments then presented on the cell’s surface via a MHC. This stimulates helper T’s and colonal production of memory B cells, as well as production of antibodies.

The difference between humoral and cellular immunity, is humoral involves antibodies, whereas cellular does not.

Question 15

What three populations are at risk of immune compromise?

Answer 15

Elderly –> as the thymus ages, it is not as productive, immune response is often delayed

Pediatrics –> underdeveloped humoral immunity, though there is some protection via maternal IgG antibodies if baby is at term and breast fed.

Immunodeficiency –> various impacts via primary congential conditions or secondary environmental conditions (i.e HIV, chemotherapy, malnutrition)

Question 16

List the 5 antibodies and their functions

Answer 16

1) IgM is the first produced in all responses. Works against carbohydrate and lipid antigens, activates complement pathway.
2) IgG is most abundant. Serves as opsonin, which helps phagocytes “grip” bacteria. Only antibody that crosses placental barrier.
3) IgH also serves as opsonin, mainly found in mucosal sites. Transmitted through breast milk.
4) IgE most often associated with allergic and parasitic responses. Triggers granulocyte release from mast cells.
5) IgD supports IgM antibodies on B cells in bone marrow, indicating when they can be released from marrow to lymphatic system.

Question 17

What is the difference between an allergic reaction and anaphylaxis?

Answer 17

An allergic reaction is localized, whereas anaphylaxis is systemic.

Question 18

Criteria for an anaphylactic reaction

Answer 18

Involvement of:

1) skin/mucosa + respiratory OR hypotension

OR

2) 2 of: skin/mucosa, respiratory, hypotension and GI systems

OR

3) hypotension post exposure to a KNOWN allergen

Question 19

Characteristics of histamine

Answer 19

Histamine is released by mast cells and basophils.
It is a major mediator of acute inflammation.
Causes increased HR, lower BP and vasodilation.

Question 20

What type of shock is anaphylaxis?

Answer 20

Distributive

Question 21

What are some high yield questions for an anaphylactic patient?

Answer 21

• exposure
• history in ICU
• epi administration
• cardiac history
• severity compared to previous episodes