Immunology of Skin/Hypersensitivity

Question 1

Characterized by the production of IgE antibodies against foreign proteins that are commonly present in the environment (e.g. pollens, animal danders, or house dust mites).

Answer 1

type I hypersensitivity

Immediate

Question 2

5 Isotypes of Antibodies

Answer 2

IgA
IgD - naive B cells
IgE
IgG
IgM - naive B cells, pentamer

Question 3

Which antibodies have no Fc receptors?

Answer 3

IgD - no constant receptor - never secreted

IgM - secreted, only secreted as pentamer hooked, constant region never exposed so no receptor

Question 4

Activated B cell secretes ______ (pentamer) → class switch recombination to make _____ (3) via T cell helping

Answer 4

Activated B cell secretes IgM (pentamer) → class switch recombination to make IgA, IgG, IgE via T cell helping

Question 5

Type I:

TH2 makes ______ → tells B cell to make ______

Answer 5

TH2 makes IL-4 → tells B cell to make IgE

Question 6

Type I:
Plasma cells make ______ → bump into granulocytes which have Fc _______ receptor, bind
Antigen recognized by ______ Ab on granulocyte

Answer 6

Plasma cells make IgE → bump into granulocytes which have Fc epsilon receptor, bind
Antigen recognized by IgE Ab on granulocyte

Question 7

Most allergens are ______

Answer 7

proteins, soluble, various functions

Question 8

IgE production is dependent on Th____ cells and that any priming that generates a Th____ response will inhibit IgE production.

Answer 8

IgE production is dependent on Th2 cells and that any priming that generates a Th1 response will inhibit IgE production.

Type I

Question 9

The main cytokines that are specifically relevant to a Th1 response include:
_____ produced by macrophages
_____ produced by T cells

Answer 9

The main cytokines that are specifically relevant to a Th1 response include:
interleukin-12 (IL-12) produced by macrophages
IFNγ produced by T cells

Question 10

By contrast, the primary cytokines relevant to a Th2 response are:
____
____
_____

Answer 10

By contrast, the primary cytokines relevant to a Th2 response are:
IL-4 / IL13
IL-5
IL-10

Question 11

Hyposensitization

Answer 11

Treatment to increase tolerance
drive response from Th2 to Treg to decrease response
NOT IL-4

Question 12

Occurs when IgG or IgM antibodies are produced against surface antigens on cells of the body. These antibodies can trigger reactions either by activating complement (e.g. autoimmune hemolytic anemia) or by facilitating the binding of natural killer cells.

Answer 12

Antibody-mediated (Type II Hypersensitivity)

Question 13

Involve the formation of immune complexes in the circulation that are not adequately cleared by macrophages or other cells of the reticuloendothelial system. The formation of immune complexes requires significant quantities of antibody and antigen. The classical diseases of this group are systemic lupus erythematosus (SLE), glomerulonephritis, and serum sickness

Answer 13

Immune Complex (Type III)

Question 14

Arthus reaction

Answer 14

Rash at site of drug injection (2nd injection)
1st inj - prime immune response, activate T cells, B cells → make Ab, memory response → massive inflammation at second injection

Question 15

3 variants of Type IV hypersensitivity

Answer 15

There are three variants of type IV hypersensitivity reaction – contact, tuberculin, and granulomatous.

Question 16

Examples of Cell Mediated Hyper.

Answer 16

contact sensitivity (e.g. to nickel or plants such as poison ivy)
the delayed hypersensitivity responses of leprosy or tuberculosis
the exaggerated response to viral infections such as measles
the persistent symptoms of allergic disease (i.e. later constriction in asthma - first is immediate)

Question 17

occurs at the site of contact with an allergen. Sensitization occurs when skin dendritic cells internalize and process epicutaneously applied hapten and migrate to the draining lymph nodes where they activate antigen-specific T cells. On re-exposure to antigen, cytokines produced by skin cells (e.g. keratinocytes, Langerhans’ cells), recruit antigen-specific, and also non-specific T cells, and macrophages.

Answer 17

Contact hypersensitivity (type IV)

Question 18

induced by CD4 T cell responses to soluble antigens from a variety of organisms. It is useful as a diagnostic test to detect infection with a number of infectious agents

Answer 18

tuberculin-type hypersensitivity (type IV)

Question 19

clinically the most important form of type IV hypersensitivity.
Persistence of antigen leads to chronic T cell activation, differentiation of macrophages into epithelioid cells, and their fusion to form giant cells → tissue pathology.

Answer 19

Granulomatous hypersensitivity (type IV)

Question 20

_______ is driven by T cell activation of macrophages, and is dependent on TNF. Inhibition of TNF leads to breakdown in _______.

Answer 20

Granuloma formation is driven by T cell activation of macrophages, and is dependent on TNF. Inhibition of TNF leads to breakdown in granulomas.

Question 21

Small molecule can elicit immune response, complex with other proteins (ie. skin) = carrier molecule to antagonize immune system

Answer 21

Hapten (type IV)

Question 22

IgG antibodies can trigger reactions either by _____ or by facilitating the binding of _______

Type ____ Hypersensitivity

Answer 22

IgG antibodies can trigger reactions either by activating complement (e.g. autoimmune hemolytic anemia) or by facilitating the binding of natural killer cells.

Type II - antibody mediated

Question 23

Type I hallmarks

Answer 23

IgE mediated - Immediate

Systemic anaphylaxis + localized anaphylaxis (hayfever, asthma, hives, food allergies, eczema)

Question 24

type 2 hallmarks

Answer 24

IgG mediated - Ab-mediated
via complement/natural killer cells

Blood transfusions, AI hemolytic anemia, erythroblastosis fetalis

Question 25

Type 3 hallmarks

Answer 25

Immune complex mediated
Need a lot of Ag-Ab

SLE, necrotizing vasculitis, RA, serum sickness

Question 26

Type IV hallmarks

Answer 26

Cell mediated
TH1 and THC cells

Contact dermatitis, tubercular lesions, or graft rejection (also crohn’s, granulomas)